2099 in Roman numerals

How MMXCIX is built

Roman numerals are written one decimal place at a time, largest first.

1. MMthousands · 2MM is 2 × M (1,000), written out 2 times.
2. XCtens · 9X before C means 100 − 10 = 90. This saves writing LXXXX.
3. IXones · 9I before X means 10 − 1 = 9. This saves writing VIIII.

2,000 + 90 + 9 = 2,099

The pairs XC and IX use subtraction: a smaller letter before a larger one is taken away from it. Only six pairs work this way: IV, IX, XL, XC, CD and CM. More on subtraction

Mistakes to avoid

• Not MMIC. It looks like a shortcut, but I may only come before V or X, not C. The correct form is MMXCIX.
• Not MMLXXXXVIIII (12 letters). That adds everything up without subtraction. The Romans sometimes wrote numbers this way, and clocks still show 4 as IIII, but today MMXCIX (6 letters) is the standard.
• There's no letter for zero. The zero is simply left out, which is why 2099 has 3 parts, not 4.