Some network call letters are essentially the Roman Numeral equivalent of their dial number – or, at least, used to be. So WXXI in Rochester, NY is Public Television Channel 21, and WLVI in Boston used to be independent TV station channel 56 (which is now the CW affiliate). Or KXXV is Channel 25 (ABC) in Waco, Texas.
edited to add:
Some languages other than English use them for the numbers of centuries, for some road numbers (mainly very low numbers on very important roads)… Often, people whose original language is one of those will do it in English. And it doesn’t seem to be terribly shocking, since you can do it for years of living in an English-speaking country without anybody thinking of mentioning it.
My Spanish-to-English translation teacher used the centuries thing as a shibboleth to discover and give low grades to the non-Anglos in her second exam, after being absurdly shocked when the best grades in the first had all gone to foreigners (six Spaniards, one Greek). Proving that “it’s not possible to perform a good translation into a language that’s not your native tongue” was more important than actually teaching, but hey, we discovered a little detail nobody had bothered to mention before.
They are sometimes used for months in date notation. I know it is common to do so in Hungary, where today’s date could be notated as 2019.II.8. Arabic numerals can also be used, but that was the notation that I saw commonly in letters and is a habit I picked up as well (along with the big endian method of writing the date out.) I have a feeling I’ve seen Roman numerals for months in other countries, but I can’t say for certain beyond Hungary.
They’re used that way sometimes in Spanish; enough to be understandable, not enough to be considered common. You’ll do it as part of some fancy document, or for clarity to make sure than everybody can tell if you’re using DD-MM or MM-DD.
Oh, yes, it was also quite customary to use three-letter abbreviations in Hungarian documents. Probably more common than the Roman numerals. So today’s date could be: 2019.2.9 or 2019.II.9 or 2019.feb.9 or 2019.február.9. (“March” gets marc and “September” gets szept, but the others are three-letter.)
Now, the Roman numeral version wasn’t the most common, but it was common enough that it made an impression on me.
Interestingly I considered starting a thread a week or so ago about this. I ran across a clock face with Roman numerals that had a weird ten: The Fall of Roman Numerals — Steve Lovelace
Big Ben has this too. I couldn’t find any other examples other than clock faces. Is it a particular “font” or is it a clockmaker invention?