## Thinking Mathematically (6th Edition)

The number of possible permutations if r objects are taken from n itself is nPr = $\frac{n!}{(n-r)!}$ The number of different ways you can arrange the books, assuming that the order of the books makes a difference to you, is: 9P9 = $\frac{9!}{(9-9)!}$ = 362880 ways