## Geometry: Common Core (15th Edition)

$220$
To evaluate a factorial expression, we multiply the number by each of the preceding integers until we get to $1$. We evaluate the factorial in the numerator and the factorial in the denominator, and then divide: $$\frac{12!}{9!3!}=\frac{12\times11\times10\times9\times8\times7\times6\times5\times4\times3\times2\times1}{(9\times8\times7\times6\times5\times4\times3\times2\times1)(3\times2\times1)}=\frac{12\times11\times10}{3\times2\times1}=220$$