# How do you evaluate 20P2?

Mar 5, 2017

Steps and result are outlined below...

#### Explanation:

The general formula for a permutation is

""_nP_r = (n!)/(n-r!)

In this case, $n = 20$ and $r = 2$, so our equation becomes

""_20P_2 = (20!)/(18!) = (20xx19) = 380