Answer
24
Work Step by Step
Use the formula of permutation: $_{n}$P$_{r}$=$\frac{n!}{(n-r)!}$. Plug in 4 for N and 3 for R:
$_{n}$P$_{r}$=$\frac{n!}{(n-r)!}$
$_{4}$P$_{3}$=$\frac{4!}{(4-3)!}$ -simplify-
$_{4}$P$_{3}$=$\frac{4!}{1!}$ -write using factorial-
$_{4}$P$_{3}$=$\frac{4*3*2*1}{1}$ -simplify-
$_{4}$P$_{3}$=24