Roman numerals
Vinculum

Using the vinculum, conventional Roman numerals are multiplied by 1,000 by adding a "bar" or "overline", thus:

The vinculum came into use in the late Republic, and it was a common alternative to the apostrophic ↀ during the Imperial era around the Roman world (M for '1000' was not in use until the Medieval period). It continued in use in the Middle Ages, though it became known more commonly as titulus, and it appears in modern editions of classical and medieval Latin texts.

In an extension of the vinculum, a three-sided box (now sometimes printed as two vertical lines and a vinculum) is used to multiply by 100,000, thus:

Vinculum notation is distinct from the custom of adding an overline to a numeral simply to indicate that it is a number. Both usages can be seen on Roman inscriptions of the same period and general location, such as on the Antonine Wall.
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