Wouldn't 999 in roman numerals simply be IM?

Answer 1

Yes but today's modern way of writing out 999 into Roman numerals is CMXCIX

But the Romans themselves would have probably calculated 999 on a abacus counting device as DCCCCLXXXXVIIII and by adding I to the right hand side and subtracting I from the left hand side of these numerals simply wrote it out as IM (-1+1000 = 999)

The rules governing today's Roman numeral system were made up during the Middle Ages but that was centuries after the decline of the Roman Empire.

Answer 2

Yes. its correct. Why to complicate the things.