## Thinking Mathematically (6th Edition)

$\frac{13!}{(13-3)!}$ Step 1: (13 -3)! = (10)! Step 2: $\frac{13!}{10!}$ = $\frac{13*12*11*10!}{10!}$ Since 10! is in the numerator and the denominator, cancel 10! 13*12*11 = 1716