2700: The Non-Roman Origins of Roman Numerals | May 12, 2024

Unlike other letter-based numerals that use the letters in ascending order of the alphabet, like Greek or Hebrew, Roman numerals are more abstracted, and somewhat systematic. For instance, X is 10, and take ½ of that for V (5), which is the top half of X. The X is probably derived from adding on an extra line at the end of a set in an early tally marks system. This works the same in M (1,000) and D (500), but not in the way that you might think. 

These letters are not tied to words, though M was reinforced by Latin ‘mille’ for ‘thousand’, and the original form of M in numerals was ↀ, half of which is D. This originated in pre-Roman Etruscan numerals, that used C (100), IↃ (500), and CIↃ (1,000) and these bracketed-I forms then were written as similar looking letters, and C reinforced by ‘centum’. In fact, though not as typically used, other forms ↁ (10,000) and ↂ (50,000) exist from this system of adding brackets. The shapes of the letters, and some Latin words may have slightly influenced the form of Roman numerals as in the case of ↀ→M, but in almost all other cases (I,V,X,L,D) these symbols only coincidentally looked like letters and have nothing to do with the words they represented.

2174: Why Merchants Prefered Roman Numerals Nov 27, 2020

While Arabic numerals eventually won out (or one out, some might say), for most of European history Roman numerals were used. Part of the reason that a few centuries ago Roman numerals were prefered was that the most common need for writing them was not with mathematics per se but with commerce. Merchants prefered to use Roman numerals because they are not so easy to counterfeit because they fall into a particular order, whereas in Arabic numerals someone could just add more digits. Moreover there were actual anti-counterfeit measures built in, such as how the terminal I (representing 1) would be written as a J for instance: XXIIJ (23) so that no one could just add extra digits.