Question

Without adding, find the sum:

1 +3 + 5+7 + 9 +11 +13+ 15 + 17+19 + 21 + 23

Answer 1

Here, there are twelve odd numbers. (n=12)

$\therefore 1+3+5+7+9+11+13+15+17+19+21+23={12}^2=144$