Vinculum (symbol)

A vinculum is a horizontal line put over a mathematical expression. It shows that it belongs together as a group. (Vinculum is Latin for "chain".)

Examples are:

1. groups of digits repeating forever, for example,

${\displaystyle {\frac {1}{3}}=0.333333\dots =0.{\overline {3}}}$

2. fractions

${\displaystyle {\frac {500}{10\times 10}}={\frac {5}{1}}=5}$

3. radicals (in the following example the quantity ${\displaystyle ab+2}$ is the radicand, and thus has a vinculum over it):

${\displaystyle {\sqrt[{n}]{ab+2}}}$