How do you ESTIMATE numbers?

Use the skill of ROUNDING

When do I use rounding?

• When the question asks you

to estimate.• When the question asks

“about how many”…?• When an exact answer isn’t

possible.• When an answer is difficult to obtain.

Try to Estimate the number of bricks used to

build this portion of a

chimney.

• 15 Bricks tall• About 4 bricks long• About 2 bricks wide

15 x 4 x 2 = 120 bricks

68,000

68,242

69,000

The population of the Sioux Reservation was 68,242. To the nearest thousand, what was the population?

68,242 is between 68,000 and 69,000, but it is closer to 68,000.

9

8

7

6

5 4

3

2

1

+0+1

Read this PoemFind your number.

Look right next door.4 or less just ignore.5 or more, add 1 more.

Now, Please take out your Math Notebook and write it down.

Round this number to the nearest

ten thousand.

Find your number.3 6 8,9 7

1Underline the number in the ten thousands place.

Round this number to the nearest

ten thousand.

Look right next door.

3 6 8,9 7 1

Circle the digit to the right of the underlined number.

Round this number to the nearest

ten thousand.

4 or less, just ignore.

3 6 8,9 7 1

8 is larger than 4 so go to the nextline of the poem.

Round this number to the nearest

ten thousand.

5 or more, add 1 more.

3 6 8,9 7 1Add 1 to the 6.

+1

Round this number to the nearest

ten thousand.

5 or more, add 1 more.

3 7 0,0 0 0Add 1 to the 6 and all the numbers

to the right of the 7 become 0’s.

The Answer

368,971 rounded to the nearest ten thousand is

3 7 0,0 0 0

Round this number to the nearest

thousand.

Find your number.

3 5, 3 2 7Underline the number in the thousands

place.

Round this number to the nearest

thousand.

Look right next door.

3 5, 3 2 7Circle to the right of the

underlined number.

Round this number to the nearest

thousand.

4 or less, just ignore.

3 5, 3 2 7

Since 3 is less than 4 we do not changethe 5.

Round this number to the nearest

thousand.

4 or less, just ignore.

3 5, 0 0 0

Change the numbers to left of 5 to 0’s.

The Answer

35,327 rounded to the nearest thousand is

3 5, 0 0 0

Round 73,852 to the nearest…

1. Ten-thousand.

2. Thousand.

3. Hundred.

4. Ten.

70,000

74,000

73,900

73,850

Round this number to the nearestdollar.

Find your number.

$ 5. 8 7

Underline the number where the dollars are.

Round this number to the nearestdollar.

Look right next door.

$ 5. 8 7

Circle to the right of the underlined number.

Round this number to the nearestdollar.

4 or less, just ignore.

$ 5. 8 78 is greater than 4 so go to the next

line of the poem.

Round this number to the nearestdollar.

5 or more, add 1 more.

$ 5. 8 7

Since 8 is greater than 5 add 1 to the 5.

+1

Round this number to the nearestdollar.

5 or more, add 1 more.

$ 6. 0 0Change the 5 to a 6 and change all the

numbers to the right to 0’s.

The Answer

$5.87 rounded to the

nearest dollar is

$ 6. 0 0

What about decimal numbers?

The same rules (and poem) apply!

Round 4.167 to the closest hundredths

4.167 Find your number

Look right next door

4.17

Special Case!Rounding a 9

Round 2.197 to the closes hundredths

Since there is a “9” in the hundredths place consider the tenth and hundredths together – 19 – do you leave it at 19 or move it to 20?

Round 4.95 to the closest tenth

Since there is a “9” in the tenth spot consider the ones and tenths

together…… should you leave it at 49 or move it to 50?

4.95 rounded to the nearest tenth is 5.0

Try these

Round to tenths:

4.56 4.6

5.32 5.3

0.98 1.0

Round to hundredths

18.784 18.78

9.456 9.46

9.997 10.00

Round this number to the nearest

tenth place.

Find your number.

4. 8 7 1Underline the number in

the tenths place.

Round this number to the nearest

tenth place.

Look right next door.

4. 8 7 1Circle to the right of the

Underlined number.

Round this number to the nearest

tenth place.

4 or less just ignore.

4. 8 7 18 is greater than 4 so go to the next

line of the poem.

Round this number to the nearest

tenth place.

5 or more, add 1 more.

4. 8 7 1Since 7 is greater than 5, add 1 to the

8.

+1

Round this number to the nearest

tenth place.

5 or more, add 1 more.

4. 9Change the 8 to a 9 and drop the

numbers to the right of the 9.

The Answer

4.871 rounded to the nearest tenth place is

4. 9

The End

Find your number.Look right next door.4 or less just ignore.

5 or more, add 1

more.

RememberIf you are asked to round to the nearest tenth…….your answer

stops at the tenth place!

Example: Round 42.73 to the closest tenth would be 42.7