CUET Preparation Today
CUET
-- Applied Mathematics - Section B2
Numbers, Quantification and Numerical Applications
If $σ(n)$ = Sum of all positive divisors of n, n ∈ N, then what is the value of $σ(18)$ ?
39
36
42
40
The correct answer is option (1) : 39
$σ(18)$
+ve divisions of 18 are $1, 2, 3, 6, 9, 18$
$∴σ(18)=1+2+3+6+9+18$
$= 39$
