31 in Roman numerals
XXXI
The number 31 is written XXXI in Roman numerals.
How XXXI breaks down
| Symbols | Value |
|---|---|
XXX | 3 × 10 = 30 |
I | 1 |
XXXI | 31 |
Every symbol here is written in descending order and simply added together — no subtractive pairs are involved.
Nearby numbers
| Number | Roman numeral |
|---|---|
| 26 | XXVI |
| 27 | XXVII |
| 28 | XXVIII |
| 29 | XXIX |
| 30 | XXX |
| 31 | XXXI |
| 32 | XXXII |
| 33 | XXXIII |
| 34 | XXXIV |
| 35 | XXXV |
| 36 | XXXVI |
The seven symbols
I | 1 | C | 100 |
V | 5 | D | 500 |
X | 10 | M | 1,000 |
L | 50 |
31 in other notations
| Roman | XXXI |
| Binary | 11111 |
| Hexadecimal | 1F |
| Octal | 37 |
| Written out | thirty-one |
Writing it by hand
Work down through the symbol values, taking as many of each as will fit before moving to the next. For 31:
3 × X = 30 remaining: 1
I = 1 remaining: 0The result reads XXXI — 4 characters, against 2 digits in Arabic numerals.
Frequently asked questions
What is 31 in Roman numerals?
XXXI
How do you read XXXI?
Work left to right, adding each symbol — except where a smaller symbol precedes a larger one, in which case it is subtracted. XXX is 30, I is 1, giving 31 in total.
How do you write 31 in words?
thirty-one.
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.