Integer If the domain is restricted to then each and every member of has one and only one corresponding member of N and by the definition of cardinal equality the two sets have equal cardinality. Integer An integer (from the Latin "integer" meaning "whole") is a number that can be written without a fractional component. For example, 21, 4, 0, and −2048 are integers, while 9.75, , and are not. The set of integers consists of zero (), the positive natural numbers (, , , …), also called "whole numbers" or "counting numbers", and their additive inverses (the negative integers, i.e.,
Quadratic integer Pell's equations, and other questions related to integral quadratic forms. The study of rings of quadratic integers is basic for many questions of algebraic number theory. Medieval Indian mathematicians had already discovered a multiplication of quadratic integers of the same , which allowed them to solve some cases of Pell's equation. The characterization of the quadratic integers was first given by Richard Dedekind in 1871. A quadratic integer is an algebraic integer of degree two. More explicitly, it is a complex number formula_1, which solves an equation of the form , with "B" and "C" integers. Each quadratic integer that