How to write 51 in Roman numerals
Roman numerals are built place by place, from the largest value to the smallest. For 51 the places are 50 (tens), 1 (ones).
- Write 50 as
L. - Write 1 as
I.
Joined together, L + I gives LI.
51 digit by digit
| Place | Value | Numeral | Rule used |
|---|---|---|---|
| tens | 50 | L | the five symbol on its own |
| ones | 1 | I | one symbol |
Check LI by reading it back
Reading LI from left to right and adding the pieces: L = 50, I = 1. Together that is 50 + 1 = 51, so LI and 51 match.
Mistakes to avoid with LI
- Only I, X and C may be placed before a larger symbol to subtract, so LI never contains forms such as VX or LC.
- Read LI 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 51
- 51 is an odd number and composite, with prime factors 3 x 17.
- In binary 51 is
110011and in hexadecimal it is33. - Written out, 51 is "fifty-one".
- The digits of 51 add up to 6, so it is divisible by 3.
Where you will see 51 in Roman numerals
Broadcast viewers identify 51 as LI during coverage of Super Bowl LI. The Roman numeral system ensures that the specific edition of the game is instantly clear regardless of the calendar year it was played.
Numbers near 51
FAQ
What is 51 in Roman numerals?
51 is written LI in Roman numerals. It is built from L (50), I (1).
How do you write 51 in lowercase Roman numerals?
Lowercase Roman numerals use the same rules, so 51 is li. 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
- 50 (L): previous page
- 52 (LII): next page
- Roman numerals chart: the full list