There are `p` copies each of `n` different books. Find the number of ways in which a nonempty selection can be made from them.

Explanation

Since, copies of the same book are identical.
`therefore`Number of selections of any number of copies of a book is p+1. similarly, in the case for each book.
Therefore, total number of selction is `(p+1)^(n)`.
But this includes a selection, which is empty i.e., zero copy of each book. exluding this, the required number of non-empty selections is `(p+1)^(n)-1`.