Number
990 in Roman numerals
990 is written CMXC
Type any other number or numeral below to convert it.
Above 3,999? Type the barred part in brackets, e.g. (IV)CC = 4,200.
How CMXC is built
Roman numerals are written one decimal place at a time, largest first.
- CMhundreds · 9C before M means 1,000 − 100 = 900. This saves writing DCCCC.
- XCtens · 9X before C means 100 − 10 = 90. This saves writing LXXXX.
900 + 90 = 990
The pairs CM and XC 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 XM. It looks like a shortcut, but X may only come before L or C, not M. The correct form is CMXC.
- Not DCCCCLXXXX (10 letters). That adds everything up without subtraction. The Romans sometimes wrote numbers this way, and clocks still show 4 as IIII, but today CMXC (4 letters) is the standard.
- There's no letter for zero. The zero is simply left out, which is why 990 has 2 parts, not 3.
About the number 990
- 990 is even and can be split into prime factors: 2 × 3 × 3 × 5 × 11, or in Roman numerals II × III × III × V × XI.
- CMXC has 4 letters. 784 of the numbers up to 1,000 have longer numerals.
Counting from 981 to 990
Every number from 981 to 990 starts CM (900); only the ending changes.
| Number | Roman numeral |
|---|---|
| 981 | CMLXXXI |
| 982 | CMLXXXII |
| 983 | CMLXXXIII |
| 984 | CMLXXXIV |
| 985 | CMLXXXV |
| 986 | CMLXXXVI |
| 987 | CMLXXXVII |
| 988 | CMLXXXVIII |
| 989 | CMLXXXIX |
| 990 | CMXC |