Question

make triangular pattern;21​

Answer 1

Answer:

This is the Triangular Number Sequence:

1, 3, 6, 10, 15, 21, 28, 36, 45, ...

It is simply the number of dots in each triangular pattern:

triangular numbers

By adding another row of dots and counting all the dots we can

find the next number of the sequence.

The first triangle has just one dot.

The second triangle has another row with 2 extra dots, making 1 + 2 = 3

The third triangle has another row with 3 extra dots, making 1 + 2 + 3 = 6

The fourth has 1 + 2 + 3 + 4 = 10

etc!