The rules governing the ancient Roman numeral system were changed in the Middle Ages presumably to make the system more compatible with the Hindu-Arabic numeral system that was being introduced into Western Europe at the time.
For example: XC = 90 and IX = 9 so it follows that if 90+9 = 99 then XC+IX must = XCIX
But in fact the ancient Romans would have calculated the equivalent of 99 on an abacus counting device as LXXXXVIIII and by placing I to each side of these numerals would have systematically reduced them to IC (100-1=99) in written format.
In fact the Latin word for IC is 'undecentum meaning one from a hundred
The Roman numeral for 99 is XCIX
99
XCIX is the number 99 (ninety-nine).
99
99 is XCIX.
No, "XCIX" is not the greatest two-digit Roman numeral number. The greatest two-digit Roman numeral number is "XC" which represents 90. "XCIX" represents 99.
The Roman numeral for 99 is XCIX
In base-ten (Arabic) numerology, the Roman numeral XCIX, equals 99.
Today it is written out as XCIX but the Romans themselves would have probably calculated it as LXXXXVIIII and then simplified it to IC (-1+100 = 99) in fact the Latin word for 99 is 'undecentum' which literally means one from a hundred.
99
XCIC is not a valid Roman Numeral - it looks like it might be 99, but that is XCIX.
That is not a properly formed Roman numeral. CC =200 XC = 90 IC = 99??? which is correctly indicated with XCIX