FrancophonIA/Vikidia-EnFr huggingface dataset:
Roman numerals are a numeral system that was used by ancient Rome. Numbers in this system uses letters from the Latin alphabet. Currently, it uses seven symbols:[1]

The Europeans still used Roman numerals even after the fall of the Roman Empire. From the 14th century, the Europeans replaced Roman numerals with Arabic numerals. However, people still uses the Roman numerals to this day.

One place they are sometimes seen is on clock faces. For example, on the clock of Big Ben, the hours from 1 to 12 are written as:

The IV and IX can be read as "one less than 5" (4) and "one less than 10" (9). On most Roman numeral clock faces, however, 4 is written as IIII.[2]

There is a simple rule, whenever the same symbol is written four times, it is replaced by subtracting it from the next higher number (5,50,50,500). That way, IV is written instead of IIII (4), XL instead of XXXX (40), etc. It is used since about the Middle Ages. Usually only one number is subtracted, not two. So 18 is usually XVIII instead of IIXX. Also, the subtraction rule is only valid for the symbol which comes right beforehand in the sequence. This means that 99 is written XCIX, and not IC.

The number zero does not have its own Roman numeral. About 725, Bede or one of his colleagues used the letter N, the abbreviation (short form) of nihil (the Latin word for "nothing").[3]

The Romans also used fractions. The most common base for fractions was 1/12, which in Latin is called uncia (ounce).

A number of numeral systems are developed for large numbers that cannot be shown with I, V, X, L, C, D and M.

One of the systems is the apostrophus,[4] in which D is written as IƆ (500) and M is written as CIƆ (1,000).[5] In this system, an extra Ɔ means 500, and multiple extra Ɔs are used to mean 5,000, 50,000 etc.

Another system is the vinculum, in which V, X, L, C, D and M are multiplied by 1,000 by adding an overline.

It is very easy to write a number as a Roman numeral. Simply substract the largest possible Roman numeral, as many times as possible from the number. This system will result in a valid Roman numeral, but will not take the subtraction rule into account.

Getting the number from the numeral is equally simple, by adding the values of the symbols.

In general, the values for 5, 50, 500,..  are not subtracted. The same number, with using the subtraction rule: