Question

Without adding find the sum is 1+3+5+7+9

Answer 1

mean is 5.
hence sum= 5* no. of terms=5*5=25

Answer 2

The sum of odd numbers is always square of the no. of odd numbers take.

sum of 'n' odd numbers = n^2

here,

n=5

sum of '5' odd numbers = 5^2
= 25