Q. The sum of all the positive divisors of $180$ excluding $1$ and itself is

Solution:

$180 =2^{2} 3^{2} 5^{1} $
$\therefore$ the sum of all the positive divisors of $180$ excluding $1$ and itself is $=\frac{2^{3}-1}{2-1} \cdot \frac{3^{3}-1}{3-1} \cdot \frac{5^{2}-1}{5-1}-181$
$=7.13 .6-181=365$