I like the decimal system because I find it easier to work with. Take the number 1992. I can say "One Thousand and Nine Hundreds and Ninety and Two" out loud, and you know which number I mean. All I need to do is count the total number of digits, to know that I am starting from Thousands rather than Ten thousands or whatever. But in roman numerals, the same number is written (I believe) as MCMXCII. I'm sure a Roman would have been able to answer questions about this number, but how would they say this number out loud. Would it be (translated into english) something like : "A Thousand and A Hundred less than a Thousand and Ten less than a Hundred and One and another One"? That's how I read it - is that what romans had to do as well?
hi! not discouraging other responses, but do check out this related post. TL;DR: the same as you would say it: "one thousand nine hundred ninety two".
Subtractive counting is possible in Latin in a few limited cases.
For example, the number eighteen could be translated as either octodecem ("eight plus ten") or duodeviginti ("two from twenty").
Likewise, it could be written out as either XVIII or IIXX, although the former is much, much more common.