Factorial
From specialfunctionswiki
Let $n$ be an integer. Then the factorial of $n$, written $n!$, is the integer $$n!=\displaystyle\prod_{k=1}^n k=n(n-1)(n-2)\ldots 3 \cdot 2 \cdot 1.$$
Let $n$ be an integer. Then the factorial of $n$, written $n!$, is the integer $$n!=\displaystyle\prod_{k=1}^n k=n(n-1)(n-2)\ldots 3 \cdot 2 \cdot 1.$$
