#### Answer

$6720$

#### Work Step by Step

Permutations Formula, page 698:
The number of permutations possible if $r$ items are taken from $n$ items is ${}_{n}P_{r}=\displaystyle \frac{n!}{(n-r)!}$.
Factorial Notation, page 696:
$n!=n(n-1)(n-2)\cdots(3)(2)(1)$
and, by definition, $0!=1$
------------------
${}_{8}P_{5}=\displaystyle \frac{8!}{(8-5)!}=\frac{8!}{3!}$
$=\displaystyle \frac{8\times 7\times 6\times 5\times 4\times 3\times 2\times 1}{3\times 2\times 1}$
$=8\times 7\times 6\times 5\times 4=6720$