Question

Can someone help me with this and explain: Compute 28P7

Answer 1

Using the factorial notation of the permutation formula, we get:

$nPr = \frac{n!}{(n - r)!}$
$28P7 = \frac{28!}{(28 - 7)!}$
$= 28 \cdot 27 \cdot 26 \cdot 25 \cdot 24 \cdot 23 \cdot 22$
$= 5 967 561 600$