Answer
42
Work Step by Step
See Factorial Notation, page 696:
$n!=n(n-1)(n-2)\cdots(3)(2)(1)$
and, by definition, $0!=1$
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$\displaystyle \frac{7!}{(7-2)!}=\frac{7!}{5!}=\frac{7\times 6\times 5\times 4\times 3\times 2\times 1}{5\times 4\times 3\times 2\times 1}$
... reduce $5\times 4\times 3\times 2$
$=7\times 6=42$