What does the overline mean in this: "What is the order of $\overline{30}$ in $\Bbb Z/54\Bbb Z$?"

Question

I apologize if this was posted already somewhere. I looked but had trouble describing it. My only question is what the overline means in this situation. I do not need help with the actual problem.

What is the order of $\overline{30}$ in $\Bbb Z/54\Bbb Z$?

Answer 1

• $\overline{30} = \left[30\right] =\left\{54m+30 \ : \ m\in\mathbb{Z}\right\}$