Answer
$560$
Work Step by Step
$C(n,r)=\displaystyle \frac{n!}{(n-r)!r!}$.
Factorials:
$n!=n(n-1)!=n(n-1)(n-2)!=...$
$n!=n(n-1)(n-2)\cdots(3)(2)(1)$
$ 0!=1,\qquad$ by definition.
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$C(16,3)=\displaystyle \frac{16!}{(16-3)!3!}=\frac{16\times 15\times 14\times(13!)}{(13!)\cdot 3!}$
$=\displaystyle \frac{16\times 15\times 14}{3\times 2\times 1}$
$=8\times 5\times 14$
= $560$