Fractielijn

Fractielijn is the term used in Dutch to describe the horizontal line that separates the numerator from the denominator in a fraction. In mathematical typography this line is often called a vinculum, and its presence signals that the numbers above and below form a single quotient.

The concept originates from the Dutch word fractie, meaning fraction. In education and publishing, fractielijn is used to discuss the standard notation of fractions, whether written by hand or printed. It helps readers distinguish a fraction from a sequence of numbers or from a division sign used in other styles of notation.

Rendering and variants vary by context and typography. The fractielijn can be a relatively long bar spanning the width of the numerator, especially in display-style fractions, or a shorter line in compact inline fractions. In informal writing, fractions are sometimes shown with a slash (for example, 3/4) instead of a full vinculum. For more complex fractions or mixed numbers, multiple stacked elements may appear with corresponding lines to maintain readability.

In mathematics and related disciplines, the fractielijn clarifies the grouping of numbers and operations. It appears in arithmetic, algebra, and number theory whenever a ratio, division, or part of a whole is expressed as a single quantity. Digital typesetting and software often implement the line through font design and layout rules; in inline text, a fraction slash may also be used to convey the same idea.

See also: Fractions, Vinculum, Fraction notation.