# Decimal separator

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Different symbols have been and are used for the decimal mark. The choice of symbol for the decimal mark affects the choice of symbol for the thousands separator used in digit grouping. Consequently the latter is treated in this article as well.

The decimal mark is mathematically a radix point. The English term decimal is limited to base ten, but the separator in non-decimal numeral systems may be referred to as a radix point. In a binary system, it is sometimes referred to as binary point.

## Contents

### History

In the Middle Ages, before printing, a bar ( ¯ ) over the units digit was used to separate the integral part of a number from its fractional part, a tradition derived from the decimal system used in Indian mathematics.[1] Its regular usage and classification can be attributed to the Persian mathematician Al-Khwarizmi.[2] It remains in common use as an underbar to superscript digits, especially for monetary pricing values. e.g. 9995 without a decimal point.

Later, a separator (ˌ) (a short, roughly vertical, ink stroke) between the units and tenths position became the norm among Islamic mathematicians. When this character was typeset, it was convenient to use the existing comma (,) or period (.) instead.

In France, the period was already in use in printing to make Roman numerals more readable, so the comma was chosen. Many other countries also chose to use the comma to mark the decimal units position, as Italy, for example.[3] It has been made standard by the ISO for international blueprints. However, English-speaking countries took the comma to separate sequences of three digits.