Using the digits $2$, $3$, $4$, $5$ and $6$, find the sum of all $5$-digit numbers that can be formed such that no two digits are same?
Why each of the number would be in any place $4!$ times and not $5!$ times?
And how to find the sum? Please can someone explain. There are many questions based on this concept. But I am not able to understand how to find sum of all the $5$-digit numbers.