Article · Wikipedia archive · Last revised Jun 8, 2026

Class number

In mathematics, class number may refer toClass number, in group theory, is the number of conjugacy classes of a group Class number, the size of the ideal class group of a number ring Class number, the number of equivalence classes of binary quadratic forms of a given discriminant

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Jun 8, 2026

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In mathematics, class number may refer to

Class number (group theory), in group theory, is the number of conjugacy classes of a group
Class number (number theory), the size of the ideal class group of a number ring
Class number (binary quadratic forms), the number of equivalence classes of binary quadratic forms of a given discriminant