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