Triangular Triangular NumbersNumbersTriangular Triangular NumbersNumbers

by Ryan and Michaelby Ryan and Michaelby Ryan and Michaelby Ryan and Michael

IntroductionIntroductionIntroductionIntroduction

Triangular numbers are numbers that are Triangular numbers are numbers that are

used to form a triangle. Triangular used to form a triangle. Triangular

numbers are 1,3,6,10 and so on.numbers are 1,3,6,10 and so on.

The Rule To Solving The Rule To Solving Triangular NumbersTriangular NumbersThe Rule To Solving The Rule To Solving Triangular NumbersTriangular Numbers

For example if you wanted to find the 57th For example if you wanted to find the 57th

triangular number, you need to add all the triangular number, you need to add all the

numbers from 1 to 57.numbers from 1 to 57.

So you add 1+2+3+4+5+6+7+8 and so So you add 1+2+3+4+5+6+7+8 and so

on.on.

Some ExamplesSome ExamplesSome ExamplesSome Examples

Finding the triangular number of 17 Finding the triangular number of 17

1+2+3+4+5+6+7+8+9+10+11+12+131+2+3+4+5+6+7+8+9+10+11+12+13

+14+15+16+17=153+14+15+16+17=153

Finding the triangular number of 14 Finding the triangular number of 14

1+2+3+4+5+6+7+8+9+10+11+12+131+2+3+4+5+6+7+8+9+10+11+12+13

+14=105+14=105

TableTableTableTable

This is the table of This is the table of the triangular the triangular

numbers from 1-20numbers from 1-20

number order # of blocks

1 1

2 3

3 6

4 10

5 15

6 21

7 28

8 36

9 45

10 55

11 66

12 78

13 91

14 105

15 120

16 136

17 153

18 171

19 189

20 209

PicturesPicturesPicturesPictures

Now for you to do Now for you to do the workthe work

Now for you to do Now for you to do the workthe work

What is the triangular number of 21 =What is the triangular number of 21 =

The Answer The Answer The Answer The Answer

If you got this answer you know how to If you got this answer you know how to

find triangular numbers.find triangular numbers.

THE ANSWER IS...... not telling youTHE ANSWER IS...... not telling you

the answer isthe answer isthe answer isthe answer is

The answer is... The answer is... 230230

Thanks For WatchingThanks For WatchingThanks For WatchingThanks For Watching

Thanks for watching!Thanks for watching!