# Exclamation mark

punctuation mark

An exclamation mark (!) is a punctuation mark. It is used to show strong emotion at the end of a sentence or after an interjection.

An exclamation mark.

The use of a space in before an exclamation mark is incorrect.

In coding, "!" sometimes means not. In mathematics, the use of an exclamation mark can be used for the factorial function (for example, ${\displaystyle n!}$).[1][2][3]

## References

1. "Compendium of Mathematical Symbols". Math Vault. 2020-03-01. Retrieved 2020-09-10.
2. "Factorial Function !". www.mathsisfun.com. Retrieved 2020-09-10.
3. Weisstein, Eric W. "Factorial". mathworld.wolfram.com. Retrieved 2020-09-10.