## College Algebra (6th Edition)

calculate n! by multiplying all positive integers from $n$ down through 1.
See p.709: If $n$ is a positive integer, the notation $n!$ (read $n$ factorial'') is the product of all positive integers from $n$ down through 1. $n!=n(n-1)(n-2)\cdots(3)(2)(1)$ Note: $0!$ (zero factorial), by definition, is 1. $0!=1$ ------------------ If n is a positive integer (it is not zero, then), calculate n! by multiplying all positive integers from $n$ down through 1.