Answer
5040
Work Step by Step
The number of possible permutations if r items are taken from n items is
nPr = $\frac{n!}{(n-r)!}$
10P4 = $\frac{10!}{(10-4)!}$ = $\frac{10*9*8*7*6!}{6!}$
Since 6! is in both the numerator and the denominator, cancel 6! in the numerator and the denominator.
10*9*8*7= 5040