Answer
90
Work Step by Step
We know that:
$_nP_r = \frac{n!}{(n-r)!}$
$_{10}P_2 = \frac{10!}{(10-2)!}$
$\frac{10!}{8!}$
We also know that:
$x! = x(x-1)(x-2)...(1)$
Thus, we have:
90
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