Congruence is an important concept in number theory. Given a positive integer M, if two integers A and B meet the requirement that A minus B can be divisible by M, then the integers A and B are said to be congruent with the module M. ..

Remainder, a mathematical term. In the division of integers, there are only two situations: divisible and non-divisible. When it is not divisible, a remainder is generated, and the remainder operation: a mod b is equal to c, which means that the remainder obtained by dividing integer a by integer b is C.