How to write 123 in Roman numerals
Roman numerals are built place by place, from the largest value to the smallest. For 123 the places are 100 (hundreds), 20 (tens), 3 (ones).
- Write 100 as
C. - Write 20 as
XX. - Write 3 as
III.
Joined together, C + XX + III gives CXXIII.
123 digit by digit
| Place | Value | Numeral | Rule used |
|---|---|---|---|
| hundreds | 100 | C | one symbol |
| tens | 20 | XX | the symbol repeated twice |
| ones | 3 | III | the symbol repeated three times (the limit) |
Check CXXIII by reading it back
Reading CXXIII from left to right and adding the pieces: C = 100, XX = 20, III = 3. Together that is 100 + 20 + 3 = 123, so CXXIII and 123 match.
Mistakes to avoid with CXXIII
- Never repeat a symbol more than three times in a row. When a fourth would be needed, the subtractive form takes over.
- Only I, X and C may be placed before a larger symbol to subtract, so CXXIII never contains forms such as VX or LC.
- Read CXXIII 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 123
- 123 is an odd number and composite, with prime factors 3 x 41.
- In binary 123 is
1111011and in hexadecimal it is7B. - Written out, 123 is "one hundred twenty-three".
- The digits of 123 add up to 6, so it is divisible by 3.
Where you will see 123 in Roman numerals
Massive compiled regulations occasionally reach part 123, which prints as CXXIII in official registers. Bureaucrats use Roman numerals for these high part numbers to maintain consistent formatting across thousands of pages of administrative law.
Numbers near 123
| Number | Roman numeral |
|---|---|
| 121 | CXXI |
| 122 | CXXII |
| 123 | CXXIII |
| 124 | CXXIV |
| 125 | CXXV |
FAQ
What is 123 in Roman numerals?
123 is written CXXIII in Roman numerals. It is built from C (100), XX (20), III (3).
How do you write 123 in lowercase Roman numerals?
Lowercase Roman numerals use the same rules, so 123 is cxxiii. 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
- 120 (CXX): previous page
- 125 (CXXV): next page
- Roman numerals chart: the full list