1. Triangular Numbers
by Ryan and Michael

2. Introduction
Triangular numbers are numbers that are used to form a triangle. Triangular numbers are 1,3,6,10 and so on.

3. The Rule To Solving Triangular Numbers
For example if you wanted to find the 57th triangular number, you need to add all the numbers from 1 to 57.
So you add and so on.

4. Some Examples
Finding the triangular number of =153
Finding the triangular number of 14
=105

5. This is the table of the triangular numbers from 1-20
number order
# of blocks 1 2 3 6 4 10 5 15 21 7 28 8 36 9 45 55 11 66 12 78 13 91 14
105
120 16
136 17
153 18
171 19
189 20
209
This is the table of the triangular numbers from 1-20

6. Pictures

7. Now for you to do the work
What is the triangular number of 21 =

8. The Answer
If you got this answer you know how to find triangular numbers.
THE ANSWER IS not telling you

9. the answer is
The answer is

10. Thanks For Watching
Thanks for watching!