Congruence Modulo \(n\).
We say \(a\) is congruent to \(b\) modulo \(n\), and write,
\begin{equation*}
a \equiv b \pmod{n}
\end{equation*}
provided \(a\) and \(b\) have the same remainder when divided by \(n\text{.}\) In other words, provided \(a\) and \(b\) belong to the same remainder class modulo \(n\text{.}\)