We say that two integers $a$ and $b$ are congruent modulo $m$ if $a − b$ is divisible by $m$. We denote this by $a≡b \pmod m$.
Example 1: $−31 ≡ 11 \pmod 7$
$11 \pmod 7$ is $4$, is it not? $-31 \neq 4$ last time I checked.
Mathematics Stack Exchange is a question and answer site for people studying math at any level and professionals in related fields. It only takes a minute to sign up.Sign up to join this community