Question

Given, $f\left(x\right)=$ sum of all natural numbers which can divide $x$ completely, then find : $f\left(12\right)$.

Answer 1

Given, $f\left(x\right)=$ sum of all natural numbers which can divide $x$ completely.

Thus $f\left(12\right)=$ Sum of all natrual numbers which can divide $12$ completely,

Divisors of $12$ are $1,2,3,4,6,12$.

Therefore, $f\left(12\right)=1+2+3+4+6+12=28$