How to write 1991 in Roman numerals
Roman numerals are built place by place, from the largest value to the smallest. For 1991 the places are 1000 (thousands), 900 (hundreds), 90 (tens), 1 (ones).
- Write 1000 as
M. - Write 900 as
CM. - Write 90 as
XC. - Write 1 as
I.
Joined together, M + CM + XC + I gives MCMXCI.
1991 digit by digit
| Place | Value | Numeral | Rule used |
|---|---|---|---|
| thousands | 1000 | M | one symbol |
| hundreds | 900 | CM | subtractive: one symbol before the ten symbol |
| tens | 90 | XC | subtractive: one symbol before the ten symbol |
| ones | 1 | I | one symbol |
Check MCMXCI by reading it back
Reading MCMXCI from left to right and adding the pieces: M = 1000, CM = 900, XC = 90, I = 1. Together that is 1000 + 900 + 90 + 1 = 1991, so MCMXCI and 1991 match.
Mistakes to avoid with MCMXCI
- Do not write the 4s and 9s additively. 1991 uses subtractive pairs (
CMfor 900,XCfor 90), not strings like IIII or VIIII. - Only I, X and C may be placed before a larger symbol to subtract, so MCMXCI never contains forms such as VX or LC.
- Read MCMXCI as one number, not letter by letter: add the values left to right, except where a smaller symbol sits before a larger one.
Facts about the number 1991
- 1991 is an odd number and composite, with prime factors 11 x 181.
- In binary 1991 is
11111000111and in hexadecimal it is7C7. - Written out, 1991 is "one thousand nine hundred ninety-one".
- The digits of 1991 add up to 20.
- As a year, 1991 was a common year with 365 days and belongs to the 20th century.
Where you will see 1991 in Roman numerals
The number 1991 is printed as MCMXCI in the colophons of limited edition books produced by private presses. Fine book printers use Roman numerals for publication years to signal craftsmanship and to distinguish their work from mass market paperbacks.
Numbers near 1991
FAQ
What is 1991 in Roman numerals?
1991 is written MCMXCI in Roman numerals. It is built from M (1000), CM (900), XC (90), I (1).
How do you write 1991 in lowercase Roman numerals?
Lowercase Roman numerals use the same rules, so 1991 is mcmxci. Lowercase is common for page numbers in a book's preface and for outline levels.
How do I convert any number to Roman numerals?
Split the number into thousands, hundreds, tens and ones, write each part with the symbols I, V, X, L, C, D and M, then join them from largest to smallest. Or paste it into the Roman numeral converter, which also converts back.
More roman numerals
- 1990 (MCMXC): previous page
- 1993 (MCMXCIII): next page
- Roman numerals chart: the full list