1,991 in Roman numerals
MCMXCI
The number 1,991 is written MCMXCI in Roman numerals. As a year it appears in copyright lines and cornerstones written this way.
How MCMXCI breaks down
| Symbols | Value |
|---|---|
M | 1,000 |
CM | 900 |
XC | 90 |
I | 1 |
MCMXCI | 1,991 |
This numeral uses the subtractive rule: a smaller symbol placed before a larger one is subtracted from it. Only six such pairs are legal — IV (4), IX (9), XL (40), XC (90), CD (400) and CM (900).
Nearby numbers
| Number | Roman numeral |
|---|---|
| 1,986 | MCMLXXXVI |
| 1,987 | MCMLXXXVII |
| 1,988 | MCMLXXXVIII |
| 1,989 | MCMLXXXIX |
| 1,990 | MCMXC |
| 1,991 | MCMXCI |
| 1,992 | MCMXCII |
| 1,993 | MCMXCIII |
| 1,994 | MCMXCIV |
| 1,995 | MCMXCV |
| 1,996 | MCMXCVI |
The seven symbols
I | 1 | C | 100 |
V | 5 | D | 500 |
X | 10 | M | 1,000 |
L | 50 |
1,991 in other notations
| Roman | MCMXCI |
| Binary | 11111000111 |
| Hexadecimal | 7C7 |
| Octal | 3707 |
| Written out | one thousand nine hundred and ninety-one |
Writing it by hand
Work down through the symbol values, taking as many of each as will fit before moving to the next. For 1,991:
M = 1000 remaining: 991
CM = 900 remaining: 91
XC = 90 remaining: 1
I = 1 remaining: 0The result reads MCMXCI — 6 characters, against 4 digits in Arabic numerals.
Frequently asked questions
What is 1,991 in Roman numerals?
MCMXCI
How do you read MCMXCI?
Work left to right, adding each symbol — except where a smaller symbol precedes a larger one, in which case it is subtracted. M is 1,000, CM is 900, XC is 90, I is 1, giving 1,991 in total.
How do you write 1,991 in words?
one thousand nine hundred and ninety-one.
Why is there no zero?
Roman numerals have no symbol for zero. The concept reached Europe only with Hindu-Arabic numerals, centuries after the system was in use — which is a large part of why it was eventually replaced for arithmetic.