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:
$P(5,4)=\dfrac{5!}{(5-4)!}\\
P(5,4)=\dfrac{5!}{1!}\\
P(5,4)=\dfrac{5\cdot4\cdot3\cdot2\cdot1}{1}\\
P(4, 4)=120$