Number
45 in Roman numerals
45 is written XLV
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 XLV is built
Roman numerals are written one decimal place at a time, largest first.
- XLtens · 4X before L means 50 − 10 = 40. This saves writing XXXX.
- Vones · 5V is 5.
40 + 5 = 45
The pair XL uses 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 VL. It looks like a shortcut, but V is never written before a larger letter to subtract. The correct form is XLV.
- Not XXXXV (5 letters). That adds everything up without subtraction. The Romans sometimes wrote numbers this way, and clocks still show 4 as IIII, but today XLV (3 letters) is the standard.
About the number 45
- 45 is odd and can be split into prime factors: 3 × 3 × 5, or in Roman numerals III × III × V.
- XLV has 3 letters. 907 of the numbers up to 1,000 have longer numerals.
Counting from 41 to 50
| Number | Roman numeral |
|---|---|
| 41 | XLI |
| 42 | XLII |
| 43 | XLIII |
| 44 | XLIV |
| 45 | XLV |
| 46 | XLVI |
| 47 | XLVII |
| 48 | XLVIII |
| 49 | XLIX |
| 50 | L |