Answer
$P(8,8) = 40,320$
Work Step by Step
Use the formula $P=\dfrac{n!}{(n-r)!}$ to obtain:
$\require{cancel}
P(8,8)
\\=\dfrac{8!}{(8-8)!}
\\=\dfrac{8(7)(6)(5)(4)(3)(2)(1)}{0!}
\\=\dfrac{40,320}{1}
\\=40,320$
We find here that when $n=r$, $P(n,r) = n!$.
