In mathematics, when an integer is not divisible by another integer, the part that is not divisible is called remainder. For example, if 17 is divided by 5, the quotient is 3 and the remainder is 2, because 17 = 5 × 3+2.

The remainder can be represented by the symbol "%",for example, 17% 5 = 2. In computer programming, the operator for finding the remainder is usually "%".

The rest have many important applications. For example, in modular operation, the remainder can represent the full equivalence of an integer in a certain number, and can also be used to judge whether a number is divisible by another number and calculate the value of a polynomial.