Factorial
The factorial of a non-negative integer n is the product of all positive integers less than or equal to n. Examples include:
|
1! = 1
2! = 2 x 1 = 2 3! = 3 x 2 x 1 = 6 4! = 4 x 3 x 2 x 1 = 24 5! = 5 x 4 x 3 x 2 x 1 = 120 6! = 6 x 5 x 4 x 3 x 2 x 1 = 720 |
By definition 0! = 1
