#### Answer

Sample answer:
"How many different 5-digit numbers can be written using 1, 2, 3, 4, and 5?"

#### Work Step by Step

The number of permutations possible
if $r$ items are taken from $n$ items is ${}_{n}P_{r}=\displaystyle \frac{n!}{(n-r)!}$.
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Sample answer:
"How many different 5-digit numbers can be written using 1, 2, 3, 4, and 5?"
${}_{5}P_{5}=\displaystyle \frac{5!}{(5-5)!}=\frac{5!}{0!}=5!$