Answer
362880
Work Step by Step
The number of possible permutations if r items are taken from n items is
nPr = $\frac{n!}{(n-r)!}$
9P9= $\frac{9!}{(9-9)!}$ = $\frac{9!}{0!}$ = $\frac{362880}{1}$ = 362880
We put 1 on the bottom since 0!=1.
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