What Is the Line Over a Repeating Decimal Called?

The vinculum has a second function in mathematics. It is placed over a series of algebraic terms to indicate that the terms should be considered as a group and is used in the same way that parenthesis might be used in an algebra problem.

When used with Roman numerals, the symbol is used to indicate that a numeral should be multiplied by 1,000. The vinculum was not used in Roman times, but it was used with Roman numerals during the Middle Ages.