Answer
Suppose we have a division problem $\frac{p}{q} = n$ with remainder $R$. To check if the answer is correct, we have to check whether $p-R = q \cdot n$ or not.
Work Step by Step
Suppose we have a division problem $\frac{p}{q} = n$ with remainder $R$.
To check if the answer is correct, if $R = 0$, we can just check whether $p = q\cdot n$ or not.
If $R$ is not $0$, we should subtract $R$ from $p$ (since $R$ is what remains from $p$ in the divison process) and check whether $p-R = q \cdot n$ or not.