Let $f(X)$ and $g(X)$ be nonzero polynomials. Then there exist polynomials $q(X)$ called the quotient and $r(X)$ called the remainder such that:

(i) $f(X)=q(X)g(X)+r(X)$ and

(ii) either $r(X)=0$ or the degree of $r(X)$ is less than the degree of $g(X)$.

To find $q(X)$ and $r(X)$, we use polynomial long division.