FANDOM


The factorial function of natural numbers is a function that takes a natural number and returns the product of all nonzero naturals less than or equal to that number. For example, $ 3! = 3 \times 2 \times 1 = 6 $.

It can be expressed in product notation as $ \prod_{n=1}^{x} n $, or in the form of a recurrence relation as $ n! = n \left( n - 1 \right)! $.

$ 0! $ is equal to one because it is the empty product.