18 in Roman numerals
XVIII
The number 18 is written XVIII in Roman numerals.
How XVIII breaks down
| Symbols | Value |
|---|---|
X | 10 |
V | 5 |
III | 3 × 1 = 3 |
XVIII | 18 |
Every symbol here is written in descending order and simply added together — no subtractive pairs are involved.
Nearby numbers
| Number | Roman numeral |
|---|---|
| 13 | XIII |
| 14 | XIV |
| 15 | XV |
| 16 | XVI |
| 17 | XVII |
| 18 | XVIII |
| 19 | XIX |
| 20 | XX |
| 21 | XXI |
| 22 | XXII |
| 23 | XXIII |
The seven symbols
I | 1 | C | 100 |
V | 5 | D | 500 |
X | 10 | M | 1,000 |
L | 50 |
18 in other notations
| Roman | XVIII |
| Binary | 10010 |
| Hexadecimal | 12 |
| Octal | 22 |
| Written out | eighteen |
Writing it by hand
Work down through the symbol values, taking as many of each as will fit before moving to the next. For 18:
X = 10 remaining: 8
V = 5 remaining: 3
3 × I = 3 remaining: 0The result reads XVIII — 5 characters, against 2 digits in Arabic numerals. The verbosity at numbers like this is precisely why positional notation replaced the system for arithmetic.
Frequently asked questions
What is 18 in Roman numerals?
XVIII
How do you read XVIII?
Work left to right, adding each symbol — except where a smaller symbol precedes a larger one, in which case it is subtracted. X is 10, V is 5, III is 3, giving 18 in total.
How do you write 18 in words?
eighteen.
Why is there no zero?
Roman numerals have no symbol for zero. The concept reached Europe only with Hindu-Arabic numerals, centuries after the system was in use — which is a large part of why it was eventually replaced for arithmetic.