Triangular Numbers

Triangular numbers are formed by the shape made from placing a dot in the corners of a triangle. The simplest form of triangle that can be made is by using three dots. Although the number one is also a triangular number.

The first numbers in a triangular number sequence are therefore 1 and 3

The next size of triangle you could make is 6

and so on.

The first four numbers in a triangular number sequence are therefore 1,3, 6 and 10.

The difference between each of the numbers increases by 1 each time.

giving this sequence of triangular numbers