If $σ(n)$ = Sum of all positive divisors of n, n ∈ N, then what is the value of $σ(18)$ ?
Answer & explanation
Correct answer: option 1
The correct answer is option (1) : 39
$σ(18)$
+ve divisions of 18 are $1, 2, 3, 6, 9, 18$
$∴σ(18)=1+2+3+6+9+18$
$= 39$