## General Science, Mathematics, and Technology## Mathematics |

## When does 0 × 0 =1? |

Factorials are the product of a given number and all the factors less than that number. The notation n! is used to express this idea. For example, 5! (five factorial) is 5 × 4 × 3 × 2 × 1 = 120. For completeness, 0! is assigned the value 1, so 0 × 0 = 1.