Answer
$362,880$
Work Step by Step
Seating in a row = arrangement. Permutations.$P(n,r)=\displaystyle \frac{n!}{(n-r)!}$.
Arranging r=$9$ from n=$9$ people,
$ P(9,9)=\displaystyle \frac{9!}{(9-9)!}\qquad$ ... by definition of factorials, $0!=1$
$=9!$
$=9\times 8\times 7\times 6\times 5\times 4\times 3\times 2\times 1$
= $362,880$
