# Class number

> Mediated Wiki article. Canonical URL: https://mediated.wiki/source/Class_number
> Markdown URL: https://mediated.wiki/source/Class_number.md
> Source: https://en.wikipedia.org/wiki/Class_number
> Source revision: 994257954
> License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/)

In [mathematics](/source/mathematics), '''class number''' may refer to

* [Class number (group theory)](/source/Class_number_(group_theory)), in group theory, is the number of conjugacy classes of a group
* [Class number (number theory)](/source/Class_number_(number_theory)), the size of the ideal class group of a number ring
* [Class number (binary quadratic forms)](/source/Class_number_(binary_quadratic_forms)), the number of equivalence classes of binary quadratic forms of a given discriminant

{{mathdab}}

---
Adapted from the Wikipedia article [Class number](https://en.wikipedia.org/wiki/Class_number) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Class_number?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.