Question

Check whether $10$ is a perfect number or not.

Answer 1

A perfect number is a positive integer whose sum of divisors is equal to twice the number.

$10$ can be written as

$$\begin{gathered} 1\times 10=10 \\ 2\times 5=10 \end{gathered}$$

The divisors of $10$ are $1,2,5,$and $10$.

If we add all the divisors of $10$,

$1+2+5+10=18$$\ne$$20=2\times 10$(Twice the number).

Thus, $10$ is not a perfect number.