# 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.[1]

An exclamation mark.

Putting a space 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, ${\displaystyle n!}$).[2][3][4]

## References

1. "Exclamation Point (or Exclamation Mark)". Grammarly. 2016-02-09. Retrieved 2020-10-17.
2. "Compendium of Mathematical Symbols". Math Vault. 2020-03-01. Retrieved 2020-09-10.
3. "Factorial Function !". www.mathsisfun.com. Retrieved 2020-09-10.
4. Weisstein, Eric W. "Factorial". mathworld.wolfram.com. Retrieved 2020-09-10.