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,

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

2. fractions

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

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

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

Other websites

• MathWorld Vinculum Entry with further (more complicated) examples
• Periodic Continued Fraction