Maths Trick

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1. The 11 Times Trick We all know the trick when multiplying by ten – add 0 to the end of the number, but did you know there is an equally easy trick for multiplying a two digit number by 11? This is it: Take the original number and imagine a space between the two digits (in this example we will use 52: 5_2 Now add the two numbers together and put them in the middle: 5_(5+2)_2 That is it – you have the answer: 572. If the numbers in the middle add up to a 2 digit number, just insert the second number and add 1 to the first: 9_(9+9)_9 (9+1)_8_9 10_8_9 1089 – It works every time. 2. Quick Square If you need to square a 2 digit number ending in 5, you can do so very easily with this trick. Mulitply the first digit by itself + 1, and put 25 on the end. That is all! 25 2 = (2x(2+1)) & 25 2 x 3 = 6 625 3. Multiply by 5

Transcript of Maths Trick

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1. The 11 Times Trick

We all know the trick when multiplying by ten – add 0 to the end of the number, but did you know there is an equally easy trick for multiplying a two digit number by 11? This is it:

Take the original number and imagine a space between the two digits (in this example we will use 52:

5_2

Now add the two numbers together and put them in the middle:

5_(5+2)_2

That is it – you have the answer: 572.

If the numbers in the middle add up to a 2 digit number, just insert the second number and add 1 to the first:

9_(9+9)_9

(9+1)_8_9

10_8_9

1089 – It works every time.

2. Quick Square

If you need to square a 2 digit number ending in 5, you can do so very easily with this trick. Mulitply the first digit by itself + 1, and put 25 on the end. That is all!

252 = (2x(2+1)) & 25

2 x 3 = 6

625

3. Multiply by 5

Most people memorize the 5 times tables very easily, but when you get in to larger numbers it gets more complex – or does it? This trick is super easy.

Take any number, then divide it by 2 (in other words, halve the number). If the result is whole, add a 0 at the end. If it is not, ignore the remainder and add a 5 at the end. It works everytime:

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2682 x 5 = (2682 / 2) & 5 or 0

2682 / 2 = 1341 (whole number so add 0)

13410

Let’s try another:

5887 x 5

2943.5 (fractional number (ignore remainder, add 5)

29435

4. Multiply by 9

This one is simple – to multiple any number between 1 and 9 by 9 hold both hands in front of your face – drop the finger that corresponds to the number you are multiplying (for example 9×3 – drop your third finger) – count the fingers before the dropped finger (in the case of 9×3 it is 2) then count the numbers after (in this case 7) – the answer is 27.

5. Multiply by 4

This is a very simple trick which may appear obvious to some, but to others it is not. The trick is to simply multiply by two, then multiply by two again:

58 x 4 = (58 x 2) + (58 x 2) = (116) + (116) = 232

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6. Calculate a Tip

If you need to leave a 15% tip, here is the easy way to do it. Work out 10% (divide the number by 10) – then add that number to half its value and you have your answer:

15% of $25 = (10% of 25) + ((10% of 25) / 2)

$2.50 + $1.25 = $3.75

7. Tough Multiplication

If you have a large number to multiply and one of the numbers is even, you can easily subdivide to get to the answer:

32 x 125, is the same as:16 x 250 is the same as:8 x 500 is the same as:4 x 1000 = 4,000

8. Dividing by 5

Dividing a large number by five is actually very simple. All you do is multiply by 2 and move the decimal point:

195 / 5

Step1: 195 * 2 = 390Step2: Move the decimal: 39.0 or just 39

2978 / 5

step 1: 2978 * 2 = 5956Step2: 595.6

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9. Subtracting from 1,000

To subtract a large number from 1,000 you can use this basic rule: subtract all but the last number from 9, then subtract the last number from 10:

1000-648

step1: subtract 6 from 9 = 3step2: subtract 4 from 9 = 5step3: subtract 8 from 10 = 2

answer: 352

10. Assorted Multiplication Rules

Multiply by 5: Multiply by 10 and divide by 2.Multiply by 6: Sometimes multiplying by 3 and then 2 is easy.Multiply by 9: Multiply by 10 and subtract the original number.Multiply by 12: Multiply by 10 and add twice the original number.Multiply by 13: Multiply by 3 and add 10 times original number.Multiply by 14: Multiply by 7 and then multiply by 2Multiply by 15: Multiply by 10 and add 5 times the original number, as above.Multiply by 16: You can double four times, if you want to. Or you can multiply by 8 and then by 2.Multiply by 17: Multiply by 7 and add 10 times original number.Multiply by 18: Multiply by 20 and subtract twice the original number (which is obvious from the first step).Multiply by 19: Multiply by 20 and subtract the original number.Multiply by 24: Multiply by 8 and then multiply by 3.Multiply by 27: Multiply by 30 and subtract 3 times the original number (which is obvious from the first step).Multiply by 45: Multiply by 50 and subtract 5 times the original number (which is obvious from the first step).Multiply by 90: Multiply by 9 (as above) and put a zero on the right.Multiply by 98: Multiply by 100 and subtract twice the original number.Multiply by 99: Multiply by 100 and subtract the original number.

Bonus: Percentages

Yanni in comment 23 gave an excellent tip for working out percentages, so I have taken the liberty of duplicating it here:

Find 7 % of 300. Sound Difficult?

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Percents: First of all you need to understand the word “Percent.” The first part is PER , as in 10 tricks per listverse page. PER = FOR EACH. The second part of the word is CENT, as in 100. Like Century = 100 years. 100 CENTS in 1 dollar… etc. Ok… so PERCENT = For Each 100.

So, it follows that 7 PERCENT of 100, is 7. (7 for each hundred, of only 1 hundred).8 % of 100 = 8. 35.73% of 100 = 35.73But how is that useful??

Back to the 7% of 300 question. 7% of the first hundred is 7. 7% of 2nd hundred is also 7, and yep, 7% of the 3rd hundred is also 7. So 7+7+7 = 21.

If 8 % of 100 is 8, it follows that 8% of 50 is half of 8 , or 4.

Break down every number that’s asked into questions of 100, if the number is less then 100, then move the decimal point accordingly.

EXAMPLES:8%200 = ? 8 + 8 = 16.8%250 = ? 8 + 8 + 4 = 20.8%25 = 2.0 (Moving the decimal back).15%300 = 15+15+15 =45.15%350 = 15+15+15+7.5 = 52.5

Also it’s usefull to know that you can always flip percents, like 3% of 100 is the same as 100% of 3.

35% of 8 is the same as 8% of 35.

http://www.glad2teach.co.uk/fast_maths_calculation_tricks.htm

3…………….

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Impress your friends with mental Math tricksNovember 11th, 2007 | by Sol |

See Math tricks on video at the Wild About Math! mathcasts page.

_____________________

Being able to perform arithmetic quickly and mentally can greatly boost your self-esteem, especially if you don’t consider yourself to be very good at Math. And, getting comfortable with arithmetic might just motivate you to dive deeper into other things mathematical.

This article presents nine ideas that will hopefully get you to look at arithmetic as a game, one in which you can see patterns among numbers and pick then apply the right trick to quickly doing the calculation.

The tricks in this article all involve multiplication.

Don’t be discouraged if the tricks seem difficult at first. Learn one trick at a time. Read the description, explanation, and examples several times for each technique you’re learning. Then make up some of your own examples and practice the technique.

As you learn and practice the tricks make sure you check your results by doing multiplication the way you’re used to, until the tricks start to become second nature. Checking your results is critically important: the last thing you want to do is learn the tricks incorrectly.

1. Multiplying by 9, or 99, or 999

Multiplying by 9 is really multiplying by 10-1.

So, 9×9 is just 9x(10-1) which is 9×10-9 which is 90-9 or 81.

Let’s try a harder example: 46×9 = 46×10-46 = 460-46 = 414.

One more example: 68×9 = 680-68 = 612.

To multiply by 99, you multiply by 100-1.

So, 46×99 = 46x(100-1) = 4600-46 = 4554.

Multiplying by 999 is similar to multiplying by 9 and by 99.

38×999 = 38x(1000-1) = 38000-38 = 37962.

2. Multiplying by 11

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To multiply a number by 11 you add pairs of numbers next to each other, except for the numbers on the edges.

Let me illustrate:

To multiply 436 by 11 go from right to left.

First write down the 6 then add 6 to its neighbor on the left, 3, to get 9.

Write down 9 to the left of 6.

Then add 4 to 3 to get 7. Write down 7.

Then, write down the leftmost digit, 4.

So, 436×11 = is 4796.

Let’s do another example: 3254×11.

The answer comes from these sums and edge numbers: (3)(3+2)(2+5)(5+4)(4) = 35794.

One more example, this one involving carrying: 4657×11.

Write down the sums and edge numbers: (4)(4+6)(6+5)(5+7)(7).

Going from right to left we write down 7.

Then we notice that 5+7=12.

So we write down 2 and carry the 1.

6+5 = 11, plus the 1 we carried = 12.

So, we write down the 2 and carry the 1.

4+6 = 10, plus the 1 we carried = 11.

So, we write down the 1 and carry the 1.

To the leftmost digit, 4, we add the 1 we carried.

So, 4657×11 = 51227 .

3. Multiplying by 5, 25, or 125

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Multiplying by 5 is just multiplying by 10 and then dividing by 2. Note: To multiply by 10 just add a 0 to the end of the number.

12×5 = (12×10)/2 = 120/2 = 60.

Another example: 64×5 = 640/2 = 320.

And, 4286×5 = 42860/2 = 21430.

To multiply by 25 you multiply by 100 (just add two 0’s to the end of the number) then divide by 4, since 100 = 25×4. Note: to divide by 4 your can just divide by 2 twice, since 2×2 = 4.

64×25 = 6400/4 = 3200/2 = 1600.

58×25 = 5800/4 = 2900/2 = 1450.

To multiply by 125, you multipy by 1000 then divide by 8 since 8×125 = 1000. Notice that 8 = 2×2x2. So, to divide by 1000 add three 0’s to the number and divide by 2 three times.

32×125 = 32000/8 = 16000/4 = 8000/2 = 4000.

48×125 = 48000/8 = 24000/4 = 12000/2 = 6000.

4. Multiplying together two numbers that differ by a small even number

This trick only works if you’ve memorized or can quickly calculate the squares of numbers. If you’re able to memorize some squares and use the tricks described later for some kinds of numbers you’ll be able to quickly multiply together many pairs of numbers that differ by 2, or 4, or 6.

Let’s say you want to calculate 12×14.

When two numbers differ by two their product is always the square of the number in between them minus 1.

12×14 = (13×13)-1 = 168.

16×18 = (17×17)-1 = 288.

99×101 = (100×100)-1 = 10000-1 = 9999

If two numbers differ by 4 then their product is the square of the number in the middle (the average of the two numbers) minus 4.

11×15 = (13×13)-4 = 169-4 = 165.

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13×17 = (15×15)-4 = 225-4 = 221.

If the two numbers differ by 6 then their product is the square of their average minus 9.

12×18 = (15×15)-9 = 216.

17×23 = (20×20)-9 = 391.

5. Squaring 2-digit numbers that end in 5

If a number ends in 5 then its square always ends in 25. To get the rest of the product take the left digit and multiply it by one more than itself.

35×35 ends in 25. We get the rest of the product by multiplying 3 by one more than 3. So, 3×4 = 12 and that’s the rest of the product. Thus, 35×35 = 1225.

To calculate 65×65, notice that 6×7 = 42 and write down 4225 as the answer.

85×85: Calculate 8×9 = 72 and write down 7225.

6. Multiplying together 2-digit numbers where the first digits are the same and the last digits sum to 10

Let’s say you want to multiply 42 by 48. You notice that the first digit is 4 in both cases. You also notice that the other digits, 2 and 8, sum to 10. You can then use this trick: multiply the first digit by one more than itself to get the first part of the answer and multiply the last digits together to get the second (right) part of the answer.

An illustration is in order:

To calculate 42×48: Multiply 4 by 4+1. So, 4×5 = 20. Write down 20.

Multiply together the last digits: 2×8 = 16. Write down 16.

The product of 42 and 48 is thus 2016.

Notice that for this particular example you could also have noticed that 42 and 48 differ by 6 and have applied technique number 4.

Another example: 64×66. 6×7 = 42. 4×6 = 24. The product is 4224.

A final example: 86×84. 8×9 = 72. 6×4 = 24. The product is 7224

7. Squaring other 2-digit numbers

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Let’s say you want to square 58. Square each digit and write a partial answer. 5×5 = 25. 8×8 = 64. Write down 2564 to start. Then, multiply the two digits of the number you’re squaring together, 5×8=40.

Double this product: 40×2=80, then add a 0 to it, getting 800.

Add 800 to 2564 to get 3364.

This is pretty complicated so let’s do more examples.

32×32. The first part of the answer comes from squaring 3 and 2.

3×3=9. 2×2 = 4. Write down 0904. Notice the extra zeros. It’s important that every square in the partial product have two digits.

Multiply the digits, 2 and 3, together and double the whole thing. 2×3x2 = 12.

Add a zero to get 120. Add 120 to the partial product, 0904, and we get 1024.

56×56. The partial product comes from 5×5 and 6×6. Write down 2536.

5×6x2 = 60. Add a zero to get 600.

56×56 = 2536+600 = 3136.

One more example: 67×67. Write down 3649 as the partial product.

6×7x2 = 42×2 = 84. Add a zero to get 840.

67×67=3649+840 = 4489.

8. Multiplying by doubling and halving

There are cases when you’re multiplying two numbers together and one of the numbers is even. In this case you can divide that number by two and multiply the other number by 2. You can do this over and over until you get to multiplication this is easy for you to do.

Let’s say you want to multiply 14 by 16. You can do this:

14×16 = 28×8 = 56×4 = 112×2 = 224.

Another example: 12×15 = 6×30 = 6×3 with a 0 at the end so it’s 180.

48×17 = 24×34 = 12×68 = 6×136 = 3×272 = 816. (Being able to calculate that 3×27 = 81 in your head is very helpful for this problem.)

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9. Multiplying by a power of 2

To multiply a number by 2, 4, 8, 16, 32, or some other power of 2 just keep doubling the product as many times as necessary. If you want to multiply by 16 then double the number 4 times since 16 = 2×2x2×2.

15×16: 15×2 = 30. 30×2 = 60. 60×2 = 120. 120×2 = 240.23×8: 23×2 = 46. 46×2 = 92. 92×2 = 184.54×8: 54×2 = 108. 108×2 = 216. 216×2 = 432.

Practice these tricks and you’ll get good at solving many different kinds of arithmetic problems in your head, or at least quickly on paper. Half the fun is identifying which trick to use. Sometimes more than one trick will apply and you’ll get to choose which one is easiest for a particular problem.

Multiplication can be a great sport! Enjoy.

See Math tricks on video at the Wild About Math! mathcasts page.

Check out these related articles:

Quick multiplication by 12: A gentle introduction to Trachtenberg speed mathematics

Help kids learn multiplication with this visual approach How to square large numbers quickly (part 1) How to get past “stupid” Math mistakes

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1. 222 Responses to “Impress your friends with mental Math tricks”

2. By Alex Kay on Nov 19, 2007 | Reply

Hey there!Just wanted to stop by and say thanks for a great post and read - math doesn’t have to be boring!

Have a nice day,Alex

3. By Sol on Nov 19, 2007 | Reply

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Alex,

You’re quite welcome. Glad you liked it.

Sol

4. By Karen (Karooch from Scraps of Mind) on Nov 19, 2007 | Reply

Hey Sol i don’t expect to be using them to impress anybody, but some of those techniques will come in very handy. Thanks a lot. I’ll give it a Stumble so others can learn them too.

5. By Sol on Nov 19, 2007 | Reply

Karen,

Thanks for the kind words and the stumbling.

Sol

6. By DJ in Houston on Nov 19, 2007 | Reply

WOW!!!

I wish I knew this while I was in school!!!

That is neat…

7. By Alan on Nov 21, 2007 | Reply

Very cool - I plan to use this as often as possible. By the way there is a minor typo…“So, 46×99 = 4600x(100-1) = 4600-46 = 4554.” should read “So, 46×99 = 46x(100-1) = 4600-46 = 4554.”

that’s ok though - this page is so cool i think i’ll let this one slide.

8. By Sol on Nov 21, 2007 | Reply

Alan,

I’m glad you like the page. I’m not seeing the error, though. Your correction looks to me the same as what I wrote. Please elaborate.

Thanks.

9. By emily on Nov 22, 2007 | Reply

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mental math tricks helps to perform arithmetic calculations quicklyMental math

10. By IB a Math Teacher on Nov 22, 2007 | Reply

Multiplying by 11 is easier when adjusting the rule for multiplying by 9. Just think of 11 as (10+1)

So 436 × 11 = 4360 + 436 = 4796…that’s the simpler way of explaining why the digits add up to each other like you wrote:

4360+ 436—–4796

11. By BPM on Nov 23, 2007 | Reply

Excellent Stumble. Thumb Up.

12. By Sol on Nov 23, 2007 | Reply

@DJ, BPM — Thanks for your kind comments.

@IB - yes, your way of showing why this “adding the pair” approach for multiplying by 11 is right on.

13. By Fred on Nov 23, 2007 | Reply

You are saying 46×99 = 4600x(100-1) when it should be 46 instead of 4600.

14. By Sol on Nov 23, 2007 | Reply

Fred, Alan:

Thanks for the correction. Now I see it!Article is now fixed.

15. By encoded on Nov 23, 2007 | Reply

These are just retarded, any idiot could think them up…

16. By rob on Nov 23, 2007 | Reply

omg the trick for multiplying squares is awesome.

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-Rob

17. By Sol on Nov 23, 2007 | Reply

Rob,

Glad you liked it.

18. By Shao Han on Nov 25, 2007 | Reply

Even primary school students know these simple tricks in China…..

19. By Sol on Nov 25, 2007 | Reply

Shao Han,

Can you recommend any books in English where I could learn about what Math Chinese students learn?

20. By BlueS on Nov 26, 2007 | Reply

Hi, I has got a problem with multipling:If i multiply some numbers in that metod some things go wrong:E.G. (agree):87 * 8188*80 + 7 = 7047

38*2038*20 + 0 = 760

E.G.(doesnt agree):56 * 1763*10 + 42 =’ 672Real: 952

75 * 8893*70 + 40 =’ 6550Real:6000

85 * 2691*20+30 =’ 1850Real: 2210

Please tell me what mistake was doing!

21. By Sol on Nov 26, 2007 | Reply

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Hi BlueS,

I assume you’re trying to use technique #4 in the article. That technique only works when the two numbers differ by a small even amount and when you can easily calculate the square of the number in the middle of the two numbers (i.e. the average).

In your example of 56×17 I see what you’re trying to do but it’s different than this trick.

Let’s look at your example:

Let a=56Let b=17

You want to calculate a*b, right?

I see that you added 7 to 56 and subtracted 7 from 17 so that you could multiply by 10. That’s a good idea.

So, you were computing (a+7)x(b-7).(a+7)x(b-7) =(axb)-(7xa)+(7xb)-49 =(axb)-7x(a-b)-49

So, (axb) = (a+7)x(b-7) + 7x(a-b)+49

Or, 56×17 = 63×10 + 7x(39)+49 = 630 + 273 + 49= 952

This approach is not easy for these two numbers.

What you could do with what you’ve noticed is to say that 56×17 = 56x(10+7) = 56×10 + 56×7= 560+392 = 952.

Does this help?

22. By Alex on Nov 26, 2007 | Reply

everyone should already know this in my opinion. it’s basic basic math.

23. By Amanda on Nov 26, 2007 | Reply

I agree that everyone should know things like how to multiply by 9 or 11. However, the method used to achieve the answer may be quite different. I was taught multiplication and agree that it is basic math, however I was never taught “tricks” such as this; basically easy ways to remember how to multiply certain numbers. I am horrible with math so

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ordinarily I cannot do multiplication in my head. However, with these tips, I may get better at it.

24. By Sol on Nov 26, 2007 | Reply

@Alex: Knowing these tricks is largely about having a relationship with numbers. I’m glad you have it but not everyone does.

@Amanda: Do report back on how these techniques help you if they do. The Vedic Math approach allows people to do multiplication without knowing more than up to 5×5 in their multiplication tables. I’ll post some Vedic Math techniques in the future.

25. By wheyyyy on Nov 26, 2007 | Reply

good tricks mate. you make it easier. nice one.

dont listen to them < >.

26. By Grinch on Nov 27, 2007 | Reply

Your annotation for the multiplying by 9’s is wrong. You have:

9×9 is just 9x(10-1) which is 9×10-9 which is 90-9 or 81

If you follow the acronym PEMDAS you would do what is in the parenthesis first and then multiply which would give you 9×9. You should have stated you need to use the distributive method. Which would mean it would read (9×10)-(9×1)= 90-9= 81.

27. By E! on Nov 28, 2007 | Reply

This is a great system developed a long time ago by Jakow Trachtenberg whilst in a Nazi camp. More info here; http://en.wikipedia.org/wiki/Trachtenberg_system

28. By EPIc on Nov 30, 2007 | Reply

there is an easier way to multiply by 9.

this is the way I learned when i was in school.

this works all the way up to 9 x 9, but if you’re in elementary school, it can come in handy.

take the number you are multiplying 9 by, and subtract one. then figure out what number plus that number equals nine.

put the first and second answer beside each other and you get tour answer.

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it’s simpler than it sounds…..example:9 x 7 = ?7 - 1 = 66 + 3 = 9the answer is 63!

9 x 3 = ?3 - 1 = 22 + 7 = 9the answer is 27!

this was the easiest way for me.

29. By Ragesh on Dec 2, 2007 | Reply

Well let me put the technique #4. Generically it uses the fact that (a+b)*(a-b) = a^2 - b^2. Here b is half of the difference between the numbers, hence a is the average. In the example where difference is 6, the minus 9 comes coz (6/2)^2 = 9. Similary it can be done for large differences also, but it depends how comfortable is one is with squaring numbers.

30. By Jon Gjengset on Dec 2, 2007 | Reply

I love this!There is one problem with technique #6 though:Take 81*89 where the first digits are equal, and where the last digits’ sum is 10.By applying your method the answer should be: (8*9)(9*1) which gives 729, when the correct answer is 7209. This happens in all cases where the product of the last digits is less than 10 (ie with 9 and 1), so a quick fix would be to always make sure you have two digits in the product, and if not then add a zero in front.

31. By Jon Gjengset on Dec 2, 2007 | Reply

Oh!I just dicovered that the problem I mentioned above also applies to technique #7!If the square of the second number is less than 10, you also have to add a zero before it in order to get the right answer:Wrong:92^2=> 180 =>3608143601174Right:92^2

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=> 180 => 36081043608464

32. By Pick Up Artist 4 Life on Dec 3, 2007 | Reply

This is great for “impressing” the somewhat math smart girls. I’m sure that the math wizzes already know this.

Bookmarked

Adam

===http://www.BecomingAPUA.com - V is the #1 Pick Up Artist===

33. By Jezz on Dec 4, 2007 | Reply

I invited #8 a long time ago… at least, I thought I did. LOL

34. By yusuf on Dec 4, 2007 | Reply

very nice math trick.. wish i had known when i was in school.. if you ask me, i would suggest to put them in elementary school’s curriculum

35. By Neil on Dec 4, 2007 | Reply

Great work, very useful.

36. By Gemeda on Dec 4, 2007 | Reply

A fantastic work! I didn’t just like it, I loved it. I have so much respect and appreciation for people like you who spend their time doing something productive on the net.

Thanks man!

37. By Nature Wallpaper on Dec 4, 2007 | Reply

finally :)!!

38. By josh on Dec 4, 2007 | Reply

have never been good with numbers, but these things do help quite a bit. how come we were never taught this at school???

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39. By Varun on Dec 4, 2007 | Reply

Anyone who has taken CAT exam in India know all these techniques and more.

40. By The Queen's English on Dec 4, 2007 | Reply

:%s/math/maths/g

41. By THE CHEAPEST FLIGHT FINDER on Dec 4, 2007 | Reply

Great post! Good tricks for life.

42. By max on Dec 4, 2007 | Reply

amazing tricks!

43. By devin on Dec 4, 2007 | Reply

heres a real trick

(a+b)^2 = 2a^2 + 2ab + b^2, so

86^2 = (80+6)^2 = 80^2 + 2*80*6 + 6^2

so 80^2 is easy 8^2+10^=64002*80*6=2*10*6*8=2*480=9606^2 = 36add

=7396

works for any number 0-99 pretty easily

44. By Virtaaj on Dec 4, 2007 | Reply

@Varun: True.. very true!

45. By naomi on Dec 5, 2007 | Reply

@ EPIc

my little brother when he was 7 taught me (age 21) the easiest way to multiply by 9 (only works up to 9×9):

Hold your ten fingers out in front of you. Now let’s say we multiply 9×3.

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Starting from your left pinkie, count three fingers (end up at your left middle finger). Fold it down. Now read your fingers. 2 (fold) 7. 27.

Try 9×6. Count from left pinkie, end up at right thumb. Fold down. Read… five fingers, fold, four fingers. 54.

EASY!

And to all of you from China, India, etc, it’s great that your primary schools taught math tricks. But many (most?) in America do not, and your comments are not constructive, almost hurtful. I go to MIT yet I still can’t do basic arithmitic in my head. Don’t belittle people because they want to learn- it’s never too late to learn!

46. By AHmed on Dec 5, 2007 | Reply

cool

47. By Zoe on Dec 5, 2007 | Reply

@ naomi

You’re not quite right about that finger trick- I use it too, and it can be easily adapted to 9×10-9×20 (it works higher than this too but takes some playing around, and not all numbers work out perfectly- I’ll let you try that!)

ie 9×13

Do the same thing for 9×3 as naomi says. Except now your leftmost pinkie is 100. Read left to right- 1 finger (100), 1 finger (10), fold, seven fingers. Answer = 117.

9×16 therefore would be left pinkie (100), four, fold, four. 144.

48. By Stock Broker on Dec 6, 2007 | Reply

Boy this was cool one. Simply splendid.After reading this my maths seem to have improved

49. By gmac refinancing a home with no money on Dec 6, 2007 | Reply

Hi My wife and I would like to thank you all for this web site. Hours of pleasure and all

50. By bill weaver on Dec 6, 2007 | Reply

BlueS, Sol -

For 56×17, the 2x rule seems easier here. 2×2x2×7 = 56, so do 7×17, then x2 three times.

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7×17 = 119 (7×10 + 7×7)x2 = 238x2 = 476x2 = 952

Great article, Sol. Lots of fun.

51. By Chris on Dec 6, 2007 | Reply

Regarding #2. A similar trick works for multiplications with 111, 1111, … you just need to make the “pipeline” longer.

Example:24253 * 111 = (2) (2+4) (2+4+2) (4+2+5) (2+5+3) (5+3) (3) = (2) (6) (8) (11) (10) (8) (3) = 2692083

It works for 101, 1001 too, where you need to “skip” a position or two when adding. Example:24253 * 101 = (2) (4) (2+2) (4+5) (2+3) (5) (3) = 2449553

52. By Yakeen on Dec 7, 2007 | Reply

I will probably need some more help on this.

53. By Mathletics..huhu.. on Dec 8, 2007 | Reply

sounds fun to me…math is really great.my fav subject wat??!!??

54. By shivashis on Dec 8, 2007 | Reply

Boy, all the posts are just great.

55. By Dale on Dec 9, 2007 | Reply

Some trippy stuff, but still cant remember it

http://dzrbenson.com/blog/

56. By Jonathan on Dec 9, 2007 | Reply

Somehow I missed this post! I use some of these, and in combination with other tricks. And I share some with students.

Fun stuff!

57. By abiel_marlon on Dec 10, 2007 | Reply

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that was a nice trick hu! have another trics there?

58. By kerato on Dec 10, 2007 | Reply

Here are some more

59. By sahil on Dec 11, 2007 | Reply

@ naomi

its a common myth in india, that indians are much better in mathematics than, especially, americans … only after coming to america did i realize how untrue this is!

Though Varun may be better in speed mathematis than all of us, the same can not be extrapolated for all indians.

60. By shestheoneforme on Dec 16, 2007 | Reply

Neat! I like things like this, that encourage you to go beyond the basics we all learned from the very beginning!Simple logical things like 57 * 9 = 57 * 10 - 57 seem so obvious once you see them, but you need to take that step!

61. By Lara on Dec 17, 2007 | Reply

A trick for multiples of 9 that I learned was to hold out your hands and bend down the number you wanted to know about.

Example:

What is the result of 5 * 9?

You bend down the fifth finger on your left hand, resulting in 4 fingers left before the bend, and 5 fingers left after the bend, equals 45.

62. By Sol on Dec 17, 2007 | Reply

Hi Lara,

Yes, that’s a nice technique for multiplying single digits by 9. It’s a nice way for children to use their kinesthetic senses to start learning arithmetic.

63. By Kannan.M on Jan 8, 2008 | Reply

Very usefullThank you

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64. By aaron on Jan 10, 2008 | Reply

i always use the 9′trick it’s easy

65. By rei on Jan 13, 2008 | Reply

Coool tricks!! these will come handy in real sitautions

66. By rei on Jan 13, 2008 | Reply

To be frank

Some of these tricks are also taught in Bangladesh at a very tender age….which we dont really recall when grown up….few tricks are published in a 5 grader book…

Nevertheless its a great effort though…

67. By amber on Jan 13, 2008 | Reply

these are some cool tricks

68. By Sol on Jan 14, 2008 | Reply

@Kannan, Aaron, Rei, Amber: I’m glad you like these tricks.

69. By Jolo on Feb 7, 2008 | Reply

Hi there

just wanted to say that your mental math tricks are magnificent. Their all useful, Thank You.I am hoping you could post more math techniques

70. By graphed on Feb 9, 2008 | Reply

wow, what a strange math! LOL!

71. By Sol on Feb 10, 2008 | Reply

Jolo,

I’m glad you like these tricks. Yes, I’ll post more over time.

72. By Matematik Özel Ders on Feb 26, 2008 | Reply

thx

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73. By Airedale on Feb 28, 2008 | Reply

Perhaps you can decipher a trick on another blog http://web.missouri.edu/~woodph/html/mult_200_300_etc_.html

He discusses multiplying,for ex.204 x 208= (2×2)(4×8x2)(4×8). My problem is that 4×8x2=64 but the answer to the problem is 42432. 24

74. By Airedale on Feb 28, 2008 | Reply

24 does not equal 64

75. By Airedale on Mar 3, 2008 | Reply

so my question is, does that trick work for numbers other than squares?

76. By celestine Umunnakwe on Mar 5, 2008 | Reply

I am not good at maths but I am very interested in knowing how to solve mathematical problems. Your site have been a very helpful tool to me. I will appreciate it if more mathematics tutorial are made available, especially on how to divide numbers quickly.

I like this site.

thanks

77. By Burton MacKenZie on Mar 30, 2008 | Reply

Nice list, some I didn’t know. Here’s one not on your list for squaring a number - http://www.burtonmackenzie.com/2008/03/more-math-in-head.html

78. By Carlos Gomez on Apr 1, 2008 | Reply

como se multiplica 93 por345

79. By abhinav on Apr 14, 2008 | Reply

this tricks are very useful for a primary student.

80. By yomanyo on Apr 15, 2008 | Reply

its very common plz.insert some better trick for both junior and senir standard.

81. By mitchelle on Apr 16, 2008 | Reply

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i love this it helped me alot

82. By mohamed fakhry on Apr 17, 2008 | Reply

this page very useful and thank you for this information

83. By Lori on Apr 23, 2008 | Reply

—Airedale I think it’s a typo or something. Cause to get the middle # u add the 3rd digit #s (in that case was 8+4). then multiply by the first digit # (which was 2) I did the example you gave plus another one. Hope it helps.

In this problem you would do the2*2=4(4+8)*2=(12)*2=244*8=32Then the answer would be 42432

Another example 209*2032*2=4(9+3)*2=(12)*2=249*3=27Then the answer would be 42427

Another one 207*2062*2=4(6+7)*2=(13)*2=266*7=42So answer would be 42642

84. By Roma on Apr 23, 2008 | Reply

this site is great! The post and some of the comments are very useful. I’ll be needing this soon in training the kids in our school in math. thanks so much!

85. By sophobic on Apr 26, 2008 | Reply

*im from the philppines*thanks for this*well done ^_^

86. By billy bob joe on Apr 28, 2008 | Reply

These tings are weird….

87. By billy bob joe on Apr 28, 2008 | Reply

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These things are REALLY weird…….

88. By anna lou on Apr 28, 2008 | Reply

wow its great!!!!!!!! i learned different tricks in solving math problems.

89. By John Morrison on Apr 29, 2008 | Reply

I have a good way to do 9 tables and multiplications. Think of 9 in this way. Subtract one from the first number and place the difference between it and 9 on the end. 2×9 is 1 and 8 or 18. 3×9 is 2 and 7 or 27. 4×9 is 3 and 6 or 36. Do you see the pattern?

90. By k.kaushik on May 1, 2008 | Reply

multypling numbers by 11

ex;54*11=59454=5+4=9at middle 9 left side 5 and right side 4thanking you

91. By k.kaushik on May 2, 2008 | Reply

Multiplying by 11, Simple trick

ex:63*11=693

Take 63 add the digits i.e 6+3=9now place the result i.e 9 in middle of 63then we get result as 693.

Hope this trick is useful.

Cheers…:)Kaushik

92. By rasi on May 25, 2008 | Reply

its really very interesting.do more tips like this

93. By ankastre, ankastre fırın, davlumbaz on Jun 4, 2008 | Reply

thank you

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94. By ankastre, ankastre fırın, davlumbaz on Jun 4, 2008 | Reply

good

95. By Ankastre fırın on Jun 4, 2008 | Reply

great..

96. By Katie on Jun 6, 2008 | Reply

Thank you so much for posting this, you genius. I hate having to count on my fingers! lol. Seriously though, this was extremely helpful. Thanks!

97. By Joseph Sahayam on Jun 15, 2008 | Reply

hi ,it is very useful.by joseph

98. By berkay on Jun 20, 2008 | Reply

thanks so much

99. By Yerli & Yabancı Şarkı Sözleri ,Programlar, Rüya tabirleri, Yemek Tarifleri on Jun 20, 2008 | Reply

thanks :))

100. By Renalyn A. Dario on Jun 22, 2008 | Reply

wow, it is so fun to learn mathematics. even someone think it so hard to learn it. But when you learn how to make it easy you will enjoy with it

101. By Xiau Ping on Jun 23, 2008 | Reply

This is a great website. Its so educational!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

102. By Xiau Ping on Jun 23, 2008 | Reply

This is sooooooooooooooooooo awesomesauce I can do math problem so much faster when I know these. Thank you so much. I truly, deeply, sincerely….. appreciate. Do you have anymore?

103. By program arşivi on Jun 30, 2008 | Reply

very nice math trick

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104. By program indir webmaster on Jun 30, 2008 | Reply

this is very good, thank you..

105. By pankaj kumar on Jul 1, 2008 | Reply

it is vry interesting wrk.i got a lot of fun & knoledge.

106. By seviye belirleme sınavı on Jul 16, 2008 | Reply

it is so fun to learn mathematics. even someone think it so hard to learn it.

107. By hania on Jul 16, 2008 | Reply

thanks

108. By pazarcık on Jul 16, 2008 | Reply

Practice these tricks and you’ll get good at solving many different kinds of arithmetic problems in your head, or at least quickly on paper. Half the fun is identifying which trick to use.

109. By Nenito J. Basaya on Jul 17, 2008 | Reply

Hello, I really like this article. I really helps me bring discussions to my students in mathematics. Also students are having fun after knowing those tricks.thank you.

110. By m.rizwan on Jul 22, 2008 | Reply

please if anybody knows that how to teach mathematics through cards,cartoon,pizza,lodo,board of chase,pls rpl me on [email protected]

111. By AKANSH on Aug 9, 2008 | Reply

16*25=?take square root4*5=20take the square of 20400=16*25

112. By John Morrison on Aug 9, 2008 | Reply

Many of your have heard of people who can look at a date from the past, and instantly call out the day of the week. I always thought this to be a very interesting skill. Let me

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tell you this, it is a great skill for impressing people. But it is also very practical and useful in daily life.

In order to do the calendar trick, you will have to have a number of very simple codes committed to memory. The first code is the month code. This code is constant and will be used throughout all your searches and mathematical steps.This is the month code:• January: 1• February: 4• March: 4• April: 0• May: 2• June: 5• July: 0• August: 3• September: 6• October: 1• November: 4• December: 6Use which ever system you wish to commit this list to memory.

This is the day code:• 1: Sunday; 1st day of week• 2: Monday; 2nd day of week, and so on.• 3: Tuesday• 4: Wednesday• 5: Thursday• 6: Friday• 7: SaturdayThe year code: this is a long list of numbers that correspond to the years 1900 to 1999,This list is broken down into 7 sections.Section 1:• 1• 7• 12• 29• 35• 40• 46• 57• 63• 68• 74• 85• 91• 96

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Section 2:• 2• 13• 19• 24• 30• 41• 47• 52• 58• 69• 75• 80• 86• 97Section 3:• 3• 8• 14• 25• 31• 36• 42• 53• 59• 64• 70• 81• 87• 92• 98

Section 4:• 9• 15• 20• 26• 37• 43• 48• 54• 65• 71• 76• 82

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• 93• 99

Section 5:• 4• 10• 21• 27• 32• 38• 55• 60• 66• 77• 83• 88• 94Section 6:• 5• 11• 16• 22• 33• 39• 44• 50• 61• 67• 72• 78• 89• 95Section 7• 0• 6• 17• 23• 28• 34• 45• 51• 56• 62• 73• 79• 84

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• 90This is a long list of numbers, but if you work on each one for a few days you will be able to recall the list. It took me only a few hours to create a link story for each list. Each story was pegged to the house list, starting from item one thru item seven.How to use the codes:In order to combine all the codes for a day you have to do the following: start with the year code. You need to know if the year is a leap year. A leap year will only effect the months of January and February. Next ask for the month, do the addition of the two. Finally add the date and cast off the sevens. The remaining number is the day of the week. April 13, 1997 would be 2 + 0 = 2. 13 + 5 = 15. Cast off the sevens and you are left with the number 1. One equals Sunday.This is the easiest code of all, the free space code.1, 8, 15, 22 and 29. This is the first position of the week for any month.I have seen other systems for the calendar trick that have used division to calculate the years. That is fine; you are free to do what you want to do.

In my opinion you would be better served to memorize the list of numbers. Did you ever wonder where the code came from? The code is based on the free spaces on the calendar.

Take a look at the calendar for the month of July. You will see that before the number 1, there are two spaces. That is because the month of July has a code of 0, but 2008 has a code of 2. Next month (August) has a code of 3, add the 2008 code for a total of 5.

If you practice the calendar trick you will master it in a week or two. Use the free spaces to learn the start of each month. For the month of August, you add the code 5 to 2, you will have 7. Now you can see that the 2nd is on Saturday. If the space the code equal 7, the code for that month is zero. September and December are 6 so when you add the 2008 code you have 8. This will mean you have a free space of 1 on their calendars. This is very easy math. To find out which day of the week Christmas falls on, add 1 to 25. Cast off the sevens from 26 and you have 5. The day code of 5 equals Thursday.

Take your time, learn from your mistakes and have fun.

113. By John Morrison on Aug 9, 2008 | Reply

please note: the nummber 49 should be included in section 5.

114. By Ria srivastava on Aug 9, 2008 | Reply

I really like this site very much.These tricks are really interesting.I am much comfortable in maths.Looking forward for more tricks.Thank you.

115. By diana on Aug 25, 2008 | Reply

Well I Think It Helped Me More On Math Because I Used To Be Dumb At It So Yeah =]

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116. By Kevin on Sep 4, 2008 | Reply

Hey frrankly, these tricks are very useful.Thanks for posting these interesting tricks.

117. By Purvesh on Sep 15, 2008 | Reply

Xcellent Site

Hats off for such a great initiative

118. By anusha on Oct 3, 2008 | Reply

hello sir can u give the solution for the following question.using 4 digit, 5 times bring all values from 0 to 50.

119. By DD on Oct 5, 2008 | Reply

Math has been easy for me and often mystify people when I calculate answers in my head. Now I’m on a quest to improve math in my head.Your web site made things easier. Nice job.Oh, by the way. I’m 74 years old and still sharp as a tack.

120. By stephen on Oct 11, 2008 | Reply

That is really interesting. My students in Ghana will enjoy that. I have more i will share with u later

121. By pankaj on Oct 14, 2008 | Reply

hey………pretty cool & nice to know these tricks…

it’s cool and smarty..

122. By Pankaj Saha on Oct 14, 2008 | Reply

Good web contents. The original root is “Vadic Mathematics”.

123. By rebecca on Oct 16, 2008 | Reply

hi…….tnx 4 that….soo now i can do my project n mathtnx

124. By charmaine on Oct 21, 2008 | Reply

i just want to say that math is now geting more and more interesting for me,, and then i discover this math tricks on how to solve the students’ disaster numbers…. wow!! i have

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learn a lot from this aricle. i’ll browse this again and continuosly browse it once more. more powers to those math-lovers who did this!! you’re one of a kind!!

125. By Dr Zoidberg on Oct 28, 2008 | Reply

I’d just like to say thanks for this. I already knew quite a few tricks, but this page taught me a few more.2435 * 3445 in your head, anyone?

126. By bridget on Nov 10, 2008 | Reply

encoded,i think it was very rude of you to put that comment. sol probly worked very hard on this.

Sol,i really liked this they helped alot,

127. By mefat on Nov 27, 2008 | Reply

who can tell me this one even i dont know it.who knows it write to my email the answer.

To people give you 25each exp 25+25=50 you have 50 now and you minus 45 now you have 5 EXP 50-45=5 now you give those 2 people 1each EXP 5-2=3 now you have 3 but you still have charge 24 each those 2 people EXP 24 + 24 = 28 plus the 3 that you have EXP 24+24=48+3=51 now WHY 51? you had 50 why 1?

128. By Gaurav Gupta on Dec 6, 2008 | Reply

Easy way to write table of 9 (use following steps 1,2,3)1: write 92): then write 1 to 9 (upside down)2a) write 9 (nine times) (upside down)3: then write 0 to 8 (downside up)

This same method can be used for writing table of 99, 999, 9999 …….if u r writing table fo 99 thn do all the above said steps. To write table of 999 on step 2a write 99 instead of 9.

129. By Pallav on Dec 26, 2008 | Reply

Sir, these tricks are really helpful.I wanna ask, if am not wrong…

“Squaring 2-digit numbers that end in 5

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If a number ends in 5 then its square always ends in 25. To get the rest of the product take the left digit and multiply it by one more than itself.

35×35 ends in 25. We get the rest of the product by multiplying 3 by one more than 3. So, 3×4 = 12 and that’s the rest of the product. Thus, 35×35 = 1225.

To calculate 65×65, notice that 6×7 = 42 and write down 4225 as the answer.

85×85: Calculate 8×9 = 72 and write down 7225.”

In this, if we take n-digit instead of 2-digit no., it still works.

for e.g.-“Say for ‘535′—-Next no. to 53 is 54, so (53 x 54 =2862).

So, 535 x 535 = 286225″

130. By Pallav on Dec 26, 2008 | Reply

Sir, in the trick—-

“Squaring 2-digit numbers that end in 5

If a number ends in 5 then its square always ends in 25. To get the rest of the product take the left digit and multiply it by one more than itself.

35×35 ends in 25. We get the rest of the product by multiplying 3 by one more than 3. So, 3×4 = 12 and that’s the rest of the product. Thus, 35×35 = 1225.

To calculate 65×65, notice that 6×7 = 42 and write down 4225 as the answer.

85×85: Calculate 8×9 = 72 and write down 7225.”

If we apply this for n-digit no., it is too applicable.

for e.g.- say for 535

(53 x (53+1)) = (53 x 54)= 2862

Thus, we have ->(535 x 535) = 286225

131. By Sol on Dec 26, 2008 | Reply

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Pallav,

You’re right on. The tricks works for 2-digit numbers because of this algebra:

(10a+5)^2 = 100a^2+100a+25

For any integer, a, 100a will end in two zeros and so will 100a^2. So, the product will always end in 25. Also, 100a^2+100a+25 factors into 100a(a+1)+25. The a(a+1) part of the product is the trick of multiplying the left digit by one more than itself.

You can do the algebra to convince yourself that this works for numbers with any number of digits.

132. By Pallav on Dec 26, 2008 | Reply

Sir,I wanna share a trick which I learnt from my friend…..

Square 2 Digit Number —->

Square a 2 Digit Number, for this example 37:Look for the nearest 10 boundaryIn this case up 3 from 37 to 40.Since you went UP 3 to 40 go DOWN 3 from 37 to 34.Now mentally multiply 34×40The way I do it is 34×10=340;Double it mentally to 680Double it again mentally to 1360This 1360 is the FIRST interim answer.37 is “3″ away from the 10 boundary 40.Square this “3″ distance from 10 boundary.3×3=9 which is the SECOND interim answer.Add the two interim answers to get the final answer.Answer: 1360 + 9 = 1369

Hope it works…

133. By ramez on Jan 2, 2009 | Reply

very fantastic tricks

134. By Anonymous on Jan 4, 2009 | Reply

Number Card MagicMake 5 cards the same as these:

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Card A 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31Card B 2 3 6 7 10 11 14 15 18 19 22 23 26 27 30 31Card C 4 5 6 7 12 13 14 15 20 21 22 23 28 29 30 31Card D 8 9 10 11 12 13 14 15 24 25 26 27 28 29 30 31Card E 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31

Get your friend to choose any number from the cards without telling you the number, but to tell you all the cards it appears on. You should be able to quickly say what number was chosen. How?

Superfast AdditionGet a friend to write down 2 numbers less than 20, one under the other without you seeing them. then your friend makes a third number by adding the first 2 together and write it below the first two. Then make a fourth number by adding the second and third, a fifth by adding the third and fourth, and so on, until there is a column of ten numbers. Now if you look at the numbers you can quickly give the total of the column. .

All you do is multiply the seventh number by 11, in the example below it is 142 x11.

Example 14+9+23+32+55+87+142+229+371+600 =1562

You can multiply by any number by 11 very quickly in your head - How? The secret is to multiply the number by 10 first and then add the number to the first result. For the example above - 10 x 142 = 1420 (the really easy bit - just add 0 to the end), then add 142 to 1420 which gives us the answer 1562 (even that bit’s not too difficult either!).

135. By Lipcy on Jan 4, 2009 | Reply

Number Card MagicMake 5 cards the same as these:

Card A 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31Card B 2 3 6 7 10 11 14 15 18 19 22 23 26 27 30 31Card C 4 5 6 7 12 13 14 15 20 21 22 23 28 29 30 31Card D 8 9 10 11 12 13 14 15 24 25 26 27 28 29 30 31Card E 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31

Get your friend to choose any number from the cards without telling you the number, but to tell you all the cards it appears on. You should be able to quickly say what number was chosen. How?

Superfast AdditionGet a friend to write down 2 numbers less than 20, one under the other without you seeing them. then your friend makes a third number by adding the first 2 together and write it below the first two. Then make a fourth number by adding the second and third, a

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fifth by adding the third and fourth, and so on, until there is a column of ten numbers. Now if you look at the numbers you can quickly give the total of the column. .

All you do is multiply the seventh number by 11, in the example below it is 142 x11.

Example 14+9+23+32+55+87+142+229+371+600 =1562

You can multiply by any number by 11 very quickly in your head - How? The secret is to multiply the number by 10 first and then add the number to the first result. For the example above - 10 x 142 = 1420 (the really easy bit - just add 0 to the end), then add 142 to 1420 which gives us the answer 1562 (even that bit’s not too difficult either!).

136. By Sol on Jan 4, 2009 | Reply

Anonymous - Thanks for the nice tricks.

137. By Likitha on Jan 8, 2009 | Reply

hello sol,thanks for the tricks and they help me a lot but I just want to say that all of them are not mental some are using paper.But anyway I learnt a lot of tricks.

thank you very much,Likitha

138. By srinivas on Jan 25, 2009 | Reply

cool maths yaar thanx to everyone great job keep it up!!!!!!!!!!!

139. By hello on Jan 29, 2009 | Reply

so coooool

140. By tong on Jan 29, 2009 | Reply

I love sharing this tricks to my students. They were all amazed with the solutions. Cold you please send me more tricks to my email address so that many students will learn more.

141. By kumar on Feb 6, 2009 | Reply

i am joined ned teacher in maths and englishup to 10th std

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i want new and easy tricks maths andenglish grammer tips

142. By Mike on Feb 8, 2009 | Reply

I am looking for the math trick that goes something like this;Pick a number from 1-100then it goes something like, multiply the number by 2 then divide by a number and then add something if the number is such and such.If you know what I mean,please E Mail me.I’ve been racking my brain for thirty years trying to remember how this trick went.

Mike

143. By John Morrison on Feb 13, 2009 | Reply

Math tricks are great for understanding the magic of math. But you should be able to do math in a logical manner. I use a method of math to train my mind for logic and pattern recognition. It is the “hidden number” system. Most people should know the times tables by heart. So for example, if you see 2*6 you will call out 12 without much thought. Sadly, there are still many adults who are not able to do simple mental math.

I have come up with a way to focus the mind on the simple parts and discover the hidden parts of math. Start with pen and paper and work your way up to mental math.

Look at this. 23*45. What are the obvious numbers? From left to right, you can see 8 and 15. Because 2*4 is 8 and 3*5 is 15. What you cannot see is the hidden number 22. The hidden number is the secret to the entire problem. It brings the left and right side numbers together. Learn to spot the hidden number and you will be able to solve 2 by 2 multiplications with ease.

Look at the problem again. 23*45 = 8-22-15. Adding for the left only the tens digits, 8 plus 2 is 10, attach the 2 in the ones column. You have partial answer of 102. Add the 1 from 15 and attach the 5 for the final answer 1035.

You will be doing math from the left side (the more natural way) and when you have a single digit number next to a pair. YOU ONLY PLACE IT ALONG SIDE. Practice with the following problems.

24*36 = Left 6, Hidden n 24, right 24. Add 6 + 2 = 8 and 4, add 2 to 4, attach the last 4.89*47 = Left 32, Hidden n 92, right 63. 32-92-63. 32+9 =41+2, 412 + 6 is 418 attach 3.56*47 = Left 20, Hidden n 59, right 42. Do it for yourself.74*85 = Left 56, Hidden n 67, right ?96*21 = Left 18, Hidden n ?, right ?

This is not a math trick, but a logical step in processing math.

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Answers:24*36 = 86489*47 = 418356*47 = 263274*85 = 629096*21 = 2016

144. By Aj on Feb 15, 2009 | Reply

Hi Sol thank you for taking the time up publish you mental maths tips I have found them very usefull, the negative comments from some of the contrnutors are not deserved your thoughts and the time you took to publish these tip are very much apprecated from this reader. Cheers Aj

145. By humaira on Feb 20, 2009 | Reply

sir, the tricks u provide are really very helpful. Their use can save our time and can be useful in competative exams.

sir, i wanna know a trick to perform the following arithmetics:1/x, where x is any real number.eg: 1/625, 1/2.303, 1/1.234 etc…

also i wanna know the tricks to calculate logs and antilogs of the numbers.

146. By Zane on Feb 23, 2009 | Reply

A professor doing amazing mental math:

http://www.ted.com/index.php/talks/arthur_benjamin_does_mathemagic.html

147. By Erasmo Caba on Mar 9, 2009 | Reply

I am not a magician but I am very interested in leaning how a person find the answer to the following:

A person asked me to:

You write down 5 numbers (5,8,10,6,2)You add these number (5+8+10+6+2)= 31then you subtract the total from the numbers (581062-31581031)

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Now this person asked me to circle one of the numbers and tell him the rest of the numbers.He was able to tell me which number I circled.

How does he did this trick? Please let me know how can he find the answer. Thanks.

148. By Erasmo on Mar 12, 2009 | Reply

I am not a magician but I am very interested in leaning how a person find the answer to the following:

A person asked me to:

You write down 5 numbers (5,8,10,6,2)You add these number (5+8+10+6+2)= 31then you subtract the total from the numbers (581062-31581031)

Now this person asked me to circle one of the numbers and tell him the rest of the numbers.He was able to tell me which number I circled.

How does he did this trick? Please let me know how can he find the answer. Thanks.

149. By Sol on Mar 12, 2009 | Reply

I’ll give you a hint. I bet the digits in the final answer always add up to a multiple of 9. Also, I bet your friend is also telling you to either not circle a 9 or to not circle a 0.

150. By William Wallace on Mar 12, 2009 | Reply

Here’s another trick my wife taught me and my son. To figure out if a number is divisible by three, simply add up the digits. If the sum is divisible by three, the original number is also divisible by three.

For example, the number 9,243,134,676 is divisible by 3, because =9+2+4+3+1+3+4+6+7+6=45, and 45/3=15.

For very large numbers, you do not need to keep a running total–you can simply discard every partial sum that is divisible by 3.

For example, using 9,243,134,676 again, discard the 9 since it is divisible by 3. Then 2+4=6, toss that partial sum, since 6 is divisible by 3, then 3, ditto, then 1+3+4+6+7=21, toss it as 21/3=7, then the last number, 6, which is also divisible by 3, so yes, 9,243,134,673 is divisible by 3.

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151. By chetanjeet on Mar 29, 2009 | Reply

CAN YOU DO THIS SUM IN LESS THAN 10 SECONDS I CAN DO THIS45696 *99999 THE ANSWER IS ;4569654303 BUT I WONT TELL YOU THE SECRET

152. By Dregun on Apr 3, 2009 | Reply

I found a way to multiply any 2 digit number by 9 really easily. The system works for 3 digit numbers up to a point and I have found the pattern but cannot decipher how to get it to work for the middle digit.

Anyways

23×9

First take the “2″ from the number “23″ and add a 1 to it..so 2+1 = 3. Take your answer “3″ and subtract it from the number you are multiplying by 9. So 23-3=20. So your answer is going to be 20x to find the “x” you simply multiply the last digit from 23 (the 3) by 9 but only keep the last value. So 3×9=27, throw away the 2 from 27 and simply put the 7 in the x 20x = 207.

42×9?

42-5 = 372*9 = 18Answer is 378

78*9

78-8 = 708*9 = 72Answer is 702

Still working on the three digit scenario but there are some rules that I have to figure out first.

153. By Eric on Apr 8, 2009 | Reply

You have spaces around the =, Alan doesn’t. I think that’s what he caught. Oh well, I didn’t notice it, thanks for posting this, it makes math so much easier.

154. By Eric on Apr 8, 2009 | Reply

Chetanjeet, not only are you obnoxious, you even got the answer wrong. 4569(6)54303 is the answer, not 4569(5)54303. Its not even a sum! Its a PRODUCT! Ugh.

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155. By Naush on Apr 22, 2009 | Reply

well Eric the correct answer is 4569(6)5430(4) not 4569(6)5430(3). to find the ans. just use n*10000-n.

156. By Naush on Apr 22, 2009 | Reply

sorry the correct ans is 4569(5)5430(4). the trick is n*100000-n

157. By cool tricks on Apr 25, 2009 | Reply

Here’s some cool tricks:-Trick No.1Multiply any no. by 12—say 4967*12.Now mentally add 0 on both sides0|4967|0Now proceed from right to left.To a number on right add twice the number to its immediate left.0+2*7=14 Write 4 carry 17+2*6+1(carry)=Write 0 carry 26+2*9+2(carry)=Write 9 carry 29+2*4+2(carry)=Write 9 carry 14+2*0+1(carry)=Write 5So the answer is 59604try 34512*12

For multiplying with 13–Follow the same rule just replace twice by thrice.

Both above tricks follow the same line of multiplication by 11.

Trick No. 2

Finding squares of two digit number.We all are comfortable with finding squares of numbers ending in 0 & 5.(5,10,15,35,25,20,40,45,55,65 etc) are known to us.So assuming this and going back to basics of squares(Square of a number(n) is sum of odd numbers(upto nth).Note–Odd number what we will consider here is (2n-1)

Now we have four categories in which rest of two digit numbers fall.===>One is one more than known squares.Like 31,41To calculate these:-(31)^2=(30)^2+31st odd number=900+(2*31-1)=961(41)^2=(40)^2+41st odd number=1600+(2*41-1)=1681===>Other is one less than known squares(44)^2=(45)^2-45th odd number=1936

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(34)^2=(35)^2-35th odd number=1156===>Next is two more than known squares32,42(32)^2=(30)^2+31st odd number+32nd odd numberBut why will I add two times.There has to be a simpler way otherwise it should be a trick.Ya there is.31st odd number+32nd odd number=4*31So,(32)^2=(30)^2+4*31=900+124=1024(42)^2=1600+4*41=1600+164=1764

===>Last one is two less than known squares33,43(33)^2=(35)^2-35th odd number-34th odd numberThis simplifies to(33)^2=(35)^2-4*34=1225-136=1125-36=1089

At Last

Trick No.3

Its easy but we don’t make use of it.It is a trick about subtraction.Ya everyone can do it but what if you do it 3 0r 4 sec faster…1178-489Its a best practice to take two digit at a time while adding or subtracting.Now we see that 78

158. By mani on May 11, 2009 | Reply

it is 4600-46 not 4600(100-1)so 46*99 gives 4559

159. By Simrat on May 23, 2009 | Reply

These tricks are fantastic.It helped me so much.Thanks a lot!

160. By arnab sarkar on Jun 5, 2009 | Reply

friends this is nicejust want to add one thing upmultiplying by 11 can b don asx(10+1)where x is ny noexample:59*11=59(10+1)or

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590+59=649easy

161. By SARWAJIT MISHRA on Jun 6, 2009 | Reply

i have no any comments. but an idea!

if u squaring a no. ends with 5 then , simply write 25 on right side and multiply the digits others then 5 to one unit greater them left digits.ex- square of 75 = 7 x 8 =5625

162. By Jason on Jun 17, 2009 | Reply

45696 *99999 is 4569554303The trick in doing this product without resorting to paper is to take the 99999 from 100000 to get 1next calculate 100000 - 45696 = 54304

Take the 1 from 45696 to get 45695 and then simply tag on the 54303 to get the answer 4569554304

Here are some simpler versions of the same approach (Vedic Maths)Using Base 108 * 9Find the differences of both 8 and 9 from 102 and 1Now cross calculate so you take the 2 from 9 and 1 from the 8 to get a 7Multiply the 2 * 1 to get 2put the 7 before the 2 to get 72

Here is an example using 1000 as the base

995 * 990Difference from a 10005 and 10Cross calculate the common number as985 (ie 995 - 10 or 990 - the 5)985 is the first part of the answer the second is 5* 10 = 050 (note you need a 3 digit answer to tag it. If the answer is 4 digits it is added)ie. 985050You can do this trick using any base but if you use say base 20 you have to multiply by 2 base 30 by 3 etc. Also if you use numbers above the base you have to add rather than subtract from the base to get the first part of the solution.Here is an example in Base 2018 * 17Cross calulate using -2 and -3 (from base 20) to get

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15Double this as you are using Base 20 to get 30for the rest of the solution work out2 * 3 = 6Answer 306Using this technique you can calulate seemingly very complex products in your head.

163. By nathaniel parcutela on Jun 20, 2009 | Reply

this is very amazing this is fantastic thank u i was able to do my assingments because of ur idea

164. By goutham on Jul 7, 2009 | Reply

MIKE u asked a question on feb 8,09 and ur question is :I am looking for the math trick that goes something like this;Pick a number from 1-100then it goes something like, multiply the number by 2 then divide by a number and then add something if the number is such and such.If you know what I mean,please E Mail me.I’ve been racking my brain for thirty years trying to remember how this trick went.

and my ans for this is

1) choose any number……..3)multiply it with 2…….3)add 500 to it…..4)divide the result by 2…….5) subtract the number what u have choosen before to the result what u have obtained now ………6) ill bet that u will get an ans of 250……

165. By Simon Wong on Jul 16, 2009 | Reply

When a 2-digit number formed by consecutive numbers(23,34,45,etc)is multipied by 99, the results are always 2 pairs.e.g. 23×99=2277,45×45=4455,78×99=7722

When a 2-digit number formed by two numbers that summed to 10(28,37,46 etc.)is multiplied by 99, the results are always pallindromes.e.g. 28×99=2772, 37×99=3663, 64×99=6336

166. By Simon Wong on Jul 17, 2009 | Reply

Thank you,Jason,for sharing your trick of solving 45696*99999. I would like to share my way of calculating 100000-45696. My trick is to do 9’s complement on all digits except

Page 47: Maths Trick

the last. Do 10’s complement for the last digit. Do it from left to right, so your brain doesn’t have to reverse the number you’ve got from the subtraction. So,10000-45696=5(4+5=9)4(5+4=9)3(6+3=9)0(9+0=9)4(6+4=10).

167. By ephemjoy on Jul 22, 2009 | Reply

5 years ago,i developed an algorithm for multiplying n-digit numbers by 11 up to 19 and it works. i just don’t know if i was the first one.

168. By ephemjoy on Jul 22, 2009 | Reply

sol, this is a very good website for math lovers.hope others would share their math secrets to us. i would share mine when i have more time for this. too much work to finish now.for the others, hope to learn more from you.thanks a lot to all math lovers who share their knowledge to others.

169. By Simon Wong on Jul 23, 2009 | Reply

Many readers of this site have learned the trick of squaring a two-digit number that ends with 5. The magic behind this trick and many other tricks is the manipulation of binomial multiplication,(a+b)(c+d). A two-digit number that ends wiwth 5 is expressed as 10n+5. The square is (10n+5)^2=100n^2+100n+25=(n(n+1))(100)+25. If n=5,(5(5+1))(100)+25=5(6)(100)+25=3000+25=3025. That’s why we multiply the tenth-digit by the next number and tag on 25.

What about squaring 51 through 59?These number are expressed by 50+n. (50+n)+100n+n^2=(25+n)(100)+n^2. If n=1,(25+1)(100)+1^2=2600+1=2601. So, to square any number from 51 to 59, add 25 to the unit digit, and tag on the square of the unit digit.

Binomial manipulation can be used for deriving other tricks such as the multiplcation of two two-digit number with the same tenth-digit, and the unit-digits that summed to 10,such as 26×24, and the multiplication of two two-digit numbers with the tenth-digits that summed to 10 and the unit digits are the same, such as 62×42.

170. By Mike on Jul 24, 2009 | Reply

Still searching for the answer to what may be perhaps a simple trick. It goes something like this:Pick a number from 1 to 100.Don’t tell the number.Then (this is the part I don’t know but goes something like) add a numberdivide by a numbermultiply by your number

Page 48: Maths Trick

the answer comes out to your original numberPlease HELP

171. By Simon Wong on Jul 24, 2009 | Reply

The multiplication of two two-digit numbers with the same tenth-digit and the unit-digits that summed to 10 can be represented by the expression (10m+a)(10m+b)=100m^2+10ma+10mb+ab=100m^2+10(a+b)+ab=100m^2+10(10)m+ab=100m^2+100m+ab=m(m+1)(100)+abe.g. 24×26=2(2+1)(100)+ 4(6)=600+24=624Therefore, the trick is multiply the tenth-digit by the next number, and tag on the product of the two digit. Is this trick similar to the square of a two-digit number that ends with 5? It is actually the same trick. 5+5=10,right?

172. By Simon Wong on Jul 29, 2009 | Reply

The multiplication of two two-digit numbers such that the unit-digits are the same and the tenth-digit summed to 10 can be expressed as (10a+m)(10b+m)=(ab)(100)+10am+10bm+m^2=(ab)(100)+(a+b)(m)(100)+m^2=(ab)(100)+(10)(10)(m)+m^2=(ab)(100)+(m)(100)+m^2=(ab+m)(100)+m^2e.g. 47×67=(4×6+7)(100)+7^2=3100+49=3149Therefore,the trick is: multiply the tenth digits, add the unit digit and then tag on the square of the unit digits.If this trick reminds you of the trick for squaring 51 through 59, it is because they are the same trick. Again, it’s because 5+5=10.

173. By gea on Jul 30, 2009 | Reply

amazing! thanks very very much! i need mental math for this entrance test i’m about to take very soon that bans the use of calculators! this is very helpful indeed:))) god bless you and your awesome brain:))

174. By Simon Wong on Jul 31, 2009 | Reply

I have a way of mutltplying a two-digit number by 99. This is not necessary better but slightly different from what has been posted earlier by other readers.Suppose you want to mutiply 49 by 99:In your mind’s eyes you see 48_ _.(49-1)Fill in the first blank the 9’s complement of the tenth digit, and you see 485_.(4+5=9)Then fill in the remaining blank the 9’s complement of the unit digit, and the answer is 4851.

175. By rachit gupta on Jul 31, 2009 | Reply

excellent trick…

Page 49: Maths Trick

176. By Simon Wong on Aug 8, 2009 | Reply

I have read Naomi’s comment dated December 5,2007. I couldn’t agree with her more that some readers from Asia have been giving destructive criticism.I am from Hong Kong. Math tricks had not been taught during my elementary and high school years. As a matter of fact, I had never passed a math test in Hong Kong. I learned most of my math tricks in the United States, and I came up with a few tricks on my own with the basic math I learned in high school. I have learn a lot from this site, and I will share all I know. I get disturbed reading negative comments ,especially from people who used to be my neighbors. Please, please ,if you know some good tricks, share with us. Let us all benefit from each other’s knowledge.

177. By prateek on Aug 17, 2009 | Reply

hey guys i m going to share a amazing trick i learnt,to multiply any no by 99999…….

what is 954862211561*999999999999—————-954862211560045137788439its damm simple!!copy the no as it is except the last digit,subtract the last digit by 1 i.e (n-1) and then again start to subtract each digit from 9 except the last digit that needs to be subtracted by 10..and yes that’s the answer!!!

lets try a simple one

865*999——-86(n-1)4/13(10-5)

864135

if the no of digits is less than the no of 9’s ie 568*9999 dont worry simply add a zero in the front and carry the process i.e 0568*9999

now if the no is 5487*999 then wat?

add 1 to the extra digit i.e (5+1) and sub the result from the remaining part of the no n then is the third part of sub from 9 excet hte last digit from 10

5/487* 999————————- 5 487 99(10)- 6 -48 7

Page 50: Maths Trick

——————-5 481 513

178. By Simon Wong on Aug 20, 2009 | Reply

Multiplcation of numbers from 11 t0 19:(10+m)(10+n)=100+10m+10n+mn=100+(m+n)(10)+mne.g. 17×14=(10+7)(10+4)=100+(7+4)(10)+7×4=100+110+28=238Mental process1. 1_ _(100)2. 21_ (100+

179. By Simon Wong on Aug 20, 2009 | Reply

My last trick was sent inadvertently before completion. Let me continue the mental process of 17X14 with a different approach:1. 1_ _ (always think of 1)2. 21_ (add the unit digits(7+4=11). Write down(mentally) the unit digit of the sum(1) as the second digit. Add the tenth digit of the sum (1)to the first digit (1).(1+1=2,hence 21_)3. 238 (Multiply the unit digits(4×7=28). Write down (mentally) the unit digit of the product (8)as the third digit. Add the tenth digit of the product(2) to the middle digit(1).(2+1=3,hence 238.)

180. By vikram on Aug 24, 2009 | Reply

yar it is so good but it must have some tricks like multiplying 2 digit numbers quicklly in head

181. By thavamani on Oct 2, 2009 | Reply

very fantastic. students may mostly benefited, if such superb sites are available. try to add some more tricks. valarka um thondu!

182. By jay on Oct 19, 2009 | Reply

thanks good site.to multiplie 142 by 11.take 142 start from righthand side first nunber is 2 add it to 4=6 add the 4 to 1= 5 remaining nunder 1.answer1562 .this works better if you start on the left.

183. By jay on Oct 20, 2009 | Reply

93×97=

93-7.97-3.

Page 51: Maths Trick

multiply7×3=21 the last two numbersin answer.cross subtract to get 90 the first two numbers.ans=9021.you can do this in your head.

184. By jay on Oct 20, 2009 | Reply

99×11=1089.from the left put down the 9.next add 9+9 18.finallyputdown the last9 9.——-1089

185. By Anonymous on Nov 4, 2009 | Reply

thank you!

186. By ABBAS ALDELAIMY on Nov 6, 2009 | Reply

Basicly, you need to understand the exact rule to correct the mistake

rule says that the numbers on the left (8 and - checksbut another condition must be met…that is the right numbers MUST add up to be 10 for the rule to hold true! which is not the case with these 2 numbersgood luck

engineer abbas aldelaimy

the

187. By Simon Wong on Nov 11, 2009 | Reply

You can prove to your friend that 10+10=10, and 10-10=20 by performing this trick:1. Show all ten digits of your hands.2. Show all ten digits of a pair of gloves.3. Put on the gloves and show your hands.(10+10=10)4. Remove the gloves and show both hands and gloves. (10-10=20)

188. By Kerin on Nov 20, 2009 | Reply

very helpful indeed

189. By Tom on Dec 2, 2009 | Reply

Page 52: Maths Trick

If you want to have fun doing mental math or practice you can use this:http://www.nixroot.com/icompute/A really a fun way to stay sharp!

190. By lex on Dec 10, 2009 | Reply

thanks tom that is cool

191. By Albert C. Añasco on Dec 13, 2009 | Reply

NICE TRICK!!!

192. By assem on Dec 24, 2009 | Reply

I love school.I love math and i has hoping to find ways to solve mentally more than the ones i found at home. 5 days! i am only 9 years and got 99 in math and 94 in average.The tricks stink.

193. By Qiant Squid on Dec 29, 2009 | Reply

These techniques are great. I did so poorly on last year’s mental math at ARML. I hope this’ll help me for this year. =)

194. By verne on Dec 29, 2009 | Reply

A trick for multiplying a 9 digit number by 142857143. For example 586362931*142857143.Write the 9 digit number twice: 586362931586362931 then divide by 7. you get 83766133083766133.

This works because 7*142857143=1000000001 then multiplying by the 9 digit number on both sides causes the 9 digit number to be repeated twice on the right. Dividing both sides by 7 yields the desired result.

This is very impressive when done on a blackboard because you write down your answer from left to right. (Especially if you do the division in your head. It’s not hard–it just takes practice.)

195. By Coolyo on Jan 16, 2010 | Reply

ja, your right about not being critical to others… im asian and IM not saying any thing so lay off

nice article

196. By sailesh on Apr 7, 2010 | Reply

Page 53: Maths Trick

suppose take a number between 10-100 then reverse the such as if you take a number 12 then make it as 21 add 11 to the obtained number 21+11=33 it is divisible by 11 for example take 45 then reverse it then it would become 54 add 11 to it then it is 66

197. By Malini on Apr 8, 2010 | Reply

Here is an alternative way to multiply a no. by 9:We have 53X9.Step 1: Take only the rightmost digit of the number 53 (i.e., 3)Find 10 - 3 = 7.53X9 = …7Step 2:Subtract the number (i.e., 53 ) by one more than the rest of the digits to its left ., in this case .,5:One more than 5 is(5 + 1 ) = 65 3 X 9 = (5 3 - 6 ) / 7 = 47 / 7 i.e., 477

Another example: 234 X 9Step 1: Take only the rightmost digit of the number 234 (i.e., 4) Find 10 -4, this is 6.234X9 = …6Step 2: Subtract the number (i.e., 234) by one more than the rest of the digits to its left ., in this case ., 23. One more than 23 is (23 + 1 ) = 24234 X 9 = (234 - 24 ) / 6= 210 / 6= 2106

198. By mm on May 8, 2010 | Reply

pls tell me how to get percentage base and ratebecause that is my only weakness in math……….. but when it comes to social studies, i can memorize a whole book…. hehehe pls. answer my comment…

199. By Rohit on Jun 2, 2010 | Reply

thank u so much for these tricks….hey i really want to know how to multiply big numbers(RANDOM) like 57 * 89..so if anyone could help me…. actually i know one of the tricks…but i want to know a more easy one…… i wil post the trick in my next comment…..so i will be grateful if anyone helps me..and thank u for the above techniques…

200. By Somnath on Jun 3, 2010 | Reply

I have a new trick.How we find sum of a number series like.1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10 = ?

So, First take next digit of last number that is 11.and then take mid digit of series that is 5.11 * 5 == 55

Page 54: Maths Trick

this is the also the sum of=1 + 2 + 3 + 4 + 5+ 6 + 7 + 8 + 9 + 10 = 55

201. By Somnath on Jun 3, 2010 | Reply

Also Middle number series like21 + 22 + 23 + 24 + 25 + 26 + 27 + 28 + 29 + 30 = ?

Simple, The tenth value of this series is 2.then value is 2 55 = 255

202. By Anonymous on Jun 8, 2010 | Reply

A few years ago I observed an activity involving the numbers 1 to 25 arranged in a 5 x 5 grid. The numbers were each a color ( I think there were 5 colors.) The teacher would leave the room and the kids would agree on a number from the board. When the teacher returned he would ask two or three questions and be able to tell the kids the number they picked.

Have you heard of this? I’d like to do it with my math class.

Steve

203. By Anonymous on Jul 7, 2010 | Reply

11x rule under 10

eg. 9*7

= the number before the 7 is 6now think in your head what plus 6 =9?its 3! so 9*7=63

eg2. 9*5 = 45 (5-1=4)(9-4=5)

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4………………….

Beauty of Mathematics Sequential Inputs of numbers with 8

1 x 8 + 1 = 9

Page 61: Maths Trick

12 x 8 + 2 = 98123 x 8 + 3 = 987

1234 x 8 + 4 = 987612345 x 8 + 5 = 98765

123456 x 8 + 6 = 9876541234567 x 8 + 7 = 9876543

12345678 x 8 + 8 = 98765432123456789 x 8 + 9 = 987654321

Sequential 1's with 91 x 9 + 2 = 11

12 x 9 + 3 = 111123 x 9 + 4 = 1111

1234 x 9 + 5 = 1111112345 x 9 + 6 = 111111

123456 x 9 + 7 = 11111111234567 x 9 + 8 = 11111111

12345678 x 9 + 9 = 111111111123456789 x 9 + 10 = 1111111111

Sequential 8's with 99 x 9 + 7 = 88

98 x 9 + 6 = 888987 x 9 + 5 = 8888

9876 x 9 + 4 = 8888898765 x 9 + 3 = 888888

987654 x 9 + 2 = 88888889876543 x 9 + 1 = 88888888

98765432 x 9 + 0 = 888888888

Numeric Palindrome with 1's1 x 1 = 1

11 x 11 = 121111 x 111 = 12321

1111 x 1111 = 123432111111 x 11111 = 123454321

111111 x 111111 = 123456543211111111 x 1111111 = 1234567654321

11111111 x 11111111 = 123456787654321111111111 x 111111111 = 12345678987654321

Without 812345679 x 9 = 111111111

12345679 x 18 = 22222222212345679 x 27 = 33333333312345679 x 36 = 444444444

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12345679 x 45 = 55555555512345679 x 54 = 66666666612345679 x 63 = 77777777712345679 x 72 = 88888888812345679 x 81 = 999999999

Sequential Inputs of 99 x 9 = 81

99 x 99 = 9801999 x 999 = 998001

9999 x 9999 = 9998000199999 x 99999 = 9999800001

999999 x 999999 = 9999980000019999999 x 9999999 = 99999980000001

99999999 x 99999999 = 9999999800000001999999999 x 999999999 = 999999998000000001

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Sequential Inputs of 66 x 7 = 42

66 x 67 = 4422666 x 667 = 444222

6666 x 6667 = 4444222266666 x 66667 = 4444422222

666666 x 666667 = 4444442222226666666 x 6666667 = 44444442222222

66666666 x 66666667 = 4444444422222222666666666 x 666666667 = 444444444222222222

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5…………..TRICKS…

Here you can find the age using some tricks. You can play these trick as instructed, with your parents or friends and prove your talent to them.

Age Calculation Age Calculation Tricks:Step1: Multiply the first number of the age by 5. (If <10, ex 5, consider it as 05. If it is >100, ex: 102, then take 10 as the first digit, 2 as the second one.)Step2: Add 3 to the result.Step3: Double the answer.Step4: Add the second digit of the number with the result.Step5: Subtract 6 from it.

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Answer: That is your age.Here we have mentioned few math trick play. You can play these tricks as instructed, with your parents or friends and prove your talent to them.

Trick Play Trick 1: Number below 10Step1: Think of a number below 10.Step2: Double the number you have thought.Step3: Add 6 with the getting result.Step4: Half the answer, that is divide it by 2.Step5: Take away the number you have thought from the answer, that is, subtract the answer from the number you have thought.

Answer: 3

Trick 2: Any NumberStep1: Think of any number.Step2: Subtract the number you have thought with 1.Step3: Multiply the result with 3.Step4: Add 12 with the result.Step5: Divide the answer by 3.Step6: Add 5 with the answer.Step7: Take away the number you have thought from the answer, that is, subtract the answer from the number you have thought.

Answer: 8

Trick 3: Any NumberStep1: Think of any number.Step2: Multiply the number you have thought with 3.Step3: Add 45 with the result.Step4: Double the result.Step5: Divide the answer by 6.Step6: Take away the number you have thought from the answer, that is, subtract the answer from the number you have thought.

Answer: 15

Trick 4: Same 3 Digit NumberStep1: Think of any 3 digit number, but each of the digits must be the same as. Ex: 333, 666.Step2: Add up the digits.Step3: Divide the 3 digit number with the digits added up.

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Answer: 37

Trick 5: 2 Single Digit NumbersStep1: Think of 2 single digit numbers.Step2: Take any one of the number among them and double it.Step3: Add 5 with the result.Step4: Multiply the result with 5.Step5: Add the second number to the answer.Step6: Subtract the answer with 4.Step7: Subtract the answer again with 21.

Answer: 2 Single Digit Numbers.

Trick 6: 1, 2, 4, 5, 7, 8Step1: Choose a number from 1 to 6.Step2: Multiply the number with 9.Step3: Multiply the result with 111.Step4: Multiply the result by 1001.Step5: Divide the answer by 7.

Answer: All the above numbers will be present.

Trick 7: 1089Step1: Think of a 3 digit number.Step2: Arrange the number in descending order.Step3: Reverse the number and subtract it with the result.Step4: Remember it and reverse the answer mentally.Step5: Add it with the result, you have got.

Answer: 1089

Trick 8: x7x11x13Step1: Think of a 3 digit number.Step2: Multiply it with x7x11x13.

Ex: Number: 456, Answer: 456456

Trick 9: x3x7x13x37Step1: Think of a 2 digit number.Step2: Multiply it with x3x7x13x37.

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Ex: Number: 45, Answer: 454545

Trick 10: 9091Step1: Think of a 5 digit number.Step2: Multiply it with 11.Step3: Multiply it with 9091.

Ex: Number: 12345, Answer: 1234512345

Trick Play Trick 1: 2's trickStep1: Think of a number .Step2: Multiply it by 3.Step3: Add 6 with the getting result.Step4: divide it by 3.Step5: Subtract it from the first number used.

Answer:2

Trick 2: Any NumberStep1: Think of any number.Step2: Double the number.Step3: Add 9 with result.Step4: sub 3 with the result.Step5: Divide the result by 2.Step6: Subtract the number with the number with first number started with.

Answer: 3

Trick 3: Any three digit NumberStep1: Add 7 to it.Step2: Multiply the number with 2.Step3: subtract 4 with the result.Step4: Divide the result by 2.Step5: Subtract it from the number started with.

Answer: 5

Math funny - Some Interesting maths tricks with phone number and missing digit. Have fun with your friends.

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Funny Tricks

Trick 1: Phone Number trick

Step1: Grab a calculator (You wont be able to do this one in your head) .Step2: Key in the first three digits of your phone number (NOT the area code-if your number is 01-123-4567, the 1st 3 digits are 123).Step3: Multiply by 80.Step4: Add 1.Step5: Multiply by 250.Step6: Add the last 3 digits of your phone number with a 0 at the end as one numberstep7: Repeat step 6step8: Subtract 250step9: Divide number by 20

Answer: The 3 digits of your phone numberFunny Trick That results on your exact phone number!!

Trick 2: Missing digit Trick

Step1: Choose a large number of six or seven digits.Step2: Take the sum of digits.Step3: Subtract sum of digits from any number chosen.Step4: Mix up the digits of resulting number.Step5: Add 25 to it.Step6: Cross out any one digit except zero.step7: Tell the sum of the digits. Subtract the sum of the digits from 25.

Answer: Inorder to find out the missing digit, subtract the sum of digits from 25. The difference is the missing digit.

Here comes a math trick to play upon calcualting your birthday date. Suprise your friends and family with this magic calculation tricks and have fun.

Math Magic Tricks

Trick 1: Birthday magic

Step1: Add 18 to your birth month.Step2: Multiply by 25.Step3: Subtract 333.Step4: Multiply by 8.step5: Subtract 554.step6: Divide by 2.step7: Add your birth date.step8: Multiply by 5.step9: Add 692.

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step10: Multiply by 20.step11: Add only the last two digits of your birth year.step12: Subtract 32940 to get your birthday!.

Example: If the answer is 123199 means that you were born on December 31, 1999. If the answer is not right, you followed the directions incorrectly or lied about your birthday.

Day of the DateHere are some shortcuts/tips to find out the day of the week from the given date. You can play these trick as instructed, with your parents or friends and prove your talent to them.

Day of the Date Day of the Week:January has 31 days. It means that every date in February will be 3 days later than the same date in January(28 is 4 weeks exactly). The below table is calculated in such a way. Remember this table which will help you to calculate. January 0February 3March 3April 6May 1June 4July 6August 2September 5October 0November 3December 5

Step1: Ask for the Date. Ex: 23rd June 1986Step2: Number of the month on the list, June is 4.Step3: Take the date of the month, that is 23Step4: Take the last 2 digits of the year, that is 86.Step5: Find out the number of leap years. Divide the last 2 digits of the year by 4, 86 divide by 4 is 21.Step6: Now add all the 4 numbers: 4 + 23 + 86 + 21 = 134.Step7: Divide 134 by 7 = 19 remainder 1.The reminder tells you the day. Sunday 0Monday 1Tuesday 2Wednesday 3Thursday 4Friday 5Saturday 6

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Answer: Monday