Displaying decimals in non-English

(for some weird reason)

Why would the coma be any weirder than the dot?

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 Iranian mathematician Al-Khwarizmi. Later, a separator (a short, roughly vertical, ink stroke) between the units and tenths position became the norm. 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[2]. It has been made standard by the ISO for international blueprints.

However, English-speaking countries took the comma to separate sequences of three digits. In the United States, the period (.), which is called a "stop" or "full stop" in some other countries, was used as the standard decimal separator. In the nations of the British Empire, although the period could be used in typewritten material, the point (middle dot: ·), which can also be called an interpunct, was preferred for the decimal separator in technologies that could accommodate it.[3]. This had the advantage of reducing confusion in the countries that used the period to separate groups of digits and it was generally clearer in handwriting (particularly when writing on a dotted baseline as on many forms). However, as the middle dot was already in common use in the mathematics world to indicate multiplication, the SI rejected this use of the middle dot as the decimal separator. However, the use of the period as decimal point was not banned. British aviation magazines thus switched to the US form in the late twentieth century.