18 in Roman Numerals
18 is written as XVIII in Roman numerals.
How XVIII is built
Roman numerals are written one place value at a time, largest first. 18 splits into 10 (tens) + 8 (ones), and each piece becomes its own group of symbols:
| Symbol | Value | Running total | Note |
|---|---|---|---|
| X | 10 | 10 | |
| V | 5 | 15 | |
| I | 1 | 16 | |
| I | 1 | 17 | |
| I | 1 | 18 |
Read left to right, the symbols add up: 10 + 5 + 1 + 1 + 1 = 18. XVIII needs no subtractive pairs: every symbol in it is simply added, because no place value of 18 is a 4 or a 9.
The symbol X (10) is the largest one used to build XVIII -- it also shows up in 81 other numbers between 1 and 100.
Frequently Asked Questions
What is 18 in Roman numerals?
18 in Roman numerals is XVIII. It is built from 5 symbol groups: X (10), V (5), I (1), I (1), I (1).
How do you write XVIII as a number?
Add the symbol values left to right, subtracting whenever a smaller symbol sits before a larger one: 10 + 5 + 1 + 1 + 1 = 18.
Does XVIII use subtractive notation?
No. None of the place values of 18 is a 4 or a 9, so every symbol in XVIII is simply added.
What comes before and after 18 in Roman numerals?
17 is XVII and 19 is XIX. Counting up in Roman numerals changes only the lowest place until it rolls over, the same way decimal digits do.
How long is XVIII compared to other numbers near 18?
XVIII is 5 characters long. Roman numerals don't get longer in a straight line with the number they represent -- XVII (17) is 4 characters and XIX (19) is 3 characters, because each number is rebuilt from scratch out of the largest symbols that fit, not incremented digit by digit.
More Number Conversions
- Roman Numeral Converter (convert any number)
- Factors of 18
Nearby numbers
16 is XVI, 17 is XVII, 19 is XIX, 20 is XX.
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