Does anyone know how Roman numerals were pronounced?

Well, English does have ace, deuce, trey for numbers in certain contexts. But the numerals used in those contexts would still be called one, two, three.

Simlarly, Irish has a separate numbering system for people — dá (trí, ceithre) bó; two (three, four) cows but beirt (triúr, ceathrar) fhear; two (three, four) men. Again, the numerals used in these contexts would have the same name.

I gave an example in the post immediately above yours. In Hebrew, fifteen is ḥamesh ‘esreh but the numerical representation of 15 is called “ṭu.”

In Chinese there are plain numeral characters for ordinary use but a parallel set of complex fancy characters for the same numerals, traditionally used in writing financial transactions. The fancy numerals were intended to prevent tampering.

But the Chinese daxie characters are still pronounced the same as the ordinary ones, right? It’s like how in English we sometimes use Arabic numerals and sometimes Roman numerals, but they’re both pronounced the same.

Japanese has both Chinese and native Japanese readings for numbers. The latter are used in more casual or colloquial speech for numbers up to ten. They also have an ornate scheme of “counters”, such that round things are counted differently from flat things, big animals are counted differently from small animals, and rabbits are counted like birds.

Chinese also has “measure words”, with different words used for round things, flat things etc. Arguably English has a limited form of something similar depending on the noun. You have to say “five loaves of bread” or “three sticks of butter”. You can’t say “five breads” or “three butters”.

That’s not because bread, butter, etc can’t be counted; it’s because they can’t be pluralised. They are what is known as mass nouns, or uncountable nouns. However much bread you have, you only ever have bread, not breads.

Isn’t it basically the same in Chinese? Words cannot be inflected to make them plural, so it is expressed in other ways.

There’s another interesting peculiarity in Japan. The proper word for numeral 4 is “shi”, but that sounds uncomfortably close to the Japanese word for “death”, so one often politely uses the euphemistic “yon” for 4 instead.

You can see this referened in a loy of places. I stumbled across it while trying to learn Japanese several years ago.

I don’t know how this is handled in Chinese, but whether a word can be pluralised and whether a word can be counted are not the same thing. There’s nothing to stop a language counting in a form like “one dog, two dog, three dog . . .”.

I have three kids and no money.
Why can’t I have no kids and three money?

True, but that language is neither English nor Chinese…

Upon reflection, maybe it is not precisely the same in English vs Chinese. In English, one says “one head of cattle”, … because in this case cattle is always plural; while in Chinese there is no singular/plural distinction but you nevertheless have to say one [head of] cattle, one [individual] dog.

Anyway, a Chinese or Japanese classifier is not a numeral. It is interesting what was noted above about numbers in Japanese having a distinct “Chinese” and a “Japanese” reading, but that is not exactly the same as a different reading for “3” and “three”.

Not quite. A bakery might say « We sell five different breads », meaning five different types of bread.

One fish, two fish, there are both red and blue fishes

Roman Numeral Latin English
I unus (oo-nus) one
II duo (du-oh) two
III tres (trays) three
IV quattuor (kwuht-tu-ohr) four
V quinque (kween-kweh) five
VI sex (sehks) six
VII septem (sehp-tehm) seven
VIII octo (ohk-to) eight
IX novem (noh-wehm) nine
X decem (deh-kehm) ten
L quinquaginta (kween-kwah-gihn-tah) fifty
C centum (kehn-tum) one hundred
D quingenti (kween-gehn-tee) five hundred
M mille (mihl-leh) thousand
Was the first thing i found.

Thanks and welcome!

A slightly different interpretation of the question:

In English, we call the typical numerals “Arabic numerals” when distinguishing them from “Roman numerals”. What did the Romans call their native numerals when distinguishing them from non-Roman numeral systems? They would’ve been aware of the Greek numeral system, if no others.

The subtractive approach to Roman numerals is an ex post attempt to invent a system for something that did not originally have it. Take, for example, the rule that you can’t skip orders of magnitude when applying the subtractive rule. 99 in the standard form of Roman numerals is XCIX - ten-short-of-a-hundred plus one-short-of-ten. An easier way to write the same number (and just as unambiguous) would be IC - one-short-of-a-hundred. But that’s taboo in the standard notation. I suppose an actual Roman would not have seen an issue with IC and would have understood it just fine. What we apply when we use “Roman numerals” today are not actual Roman numerals but a much later standardisation of it after we imposed made-up rules onto actual ancient practices.

I have always appreciated XIIX.

There is a theory (?) that the Roman symbols are related to Etruscan ones. See also A Dictionary of Greek and Roman Antiquities (1890), LOGI´STICA

They used a similar system for dates – counting up to and away from the Ides, the Nones and the Kalends.

It seems strange to much of the World that Americans write dates Month,Day,Year, but I explain to them that Americans pronounce their dates that way (“March 15, 44BC”).

I am trying to get over the idea that some people think the Romans said things like “eye vee” for IV and “ecks eye” for 11.