Modular arithmetic is a generalization of odd and even. We say that two integers, x and y, are congruent modulo a third integer n if and only if x - y is divisible by n. For example, 5 and 8 are congruent modulo 3 because 5 - 8 = -3 is divisible by 3....

Modular arithmetic (sometimes called modulo arithmetic, or clock arithmetic) is a system of arithmetic for integers, where numbers "wrap around" after they reach a certain value — the modulus. Modular arithmetic was introduced by Carl Friedrich...