Answer
$120$
Work Step by Step
Use the formula $P(n,r)=\dfrac{n!}{(n-r)!}$.
Here we have $n=5$ and $r=4$.:
Substitute these values into the formula above to obtain:
$P(5,4)=\dfrac{5!}{(5-4)!}\\$
$P(5,4)=\dfrac{5!}{1!}\\$
$P(5,4)=\dfrac{5\cdot4\cdot3\cdot2\cdot1}{1}$
Cancel out the common factors to obtain:
$P(5, 4) = 5\cdot4\cdot3\cdot2\\
P(5, 4) = 120$
