Find the integer $n$, $0 \le n \le 9$, that satisfies \[n \equiv -2187 \pmod{10}.\]
I know that $n \equiv -2187 \pmod{10}$ means that $n$ and $-2187$ have the same remainder when divided by $10$. So I can ignore the $-2187$ and focus on the remainder. I can find the remainder by dividing by $10$ and looking at the last digit. That means $n \equiv 3 \pmod{10}$. So the integer $n$ that satisfies the given equation is $n = 3$. 