What are the two triangular numbers that add up to 24?

Answer 1

The triangular numbers up to and immediately beyond 24 are

1 = 1

1+2 = 3

1+2+3 = 6

1+2+3+4 = 10

1+2+3+4+5 = 15

1+2+3+4+5+6 = 21

1+2+3+4+5+6+7 = 28

So, of these, only 3 + 21 can be added together to make 24