81 in Roman numerals
LXXXI
The number 81 is written LXXXI in Roman numerals.
How LXXXI breaks down
| Symbols | Value |
|---|---|
L | 50 |
XXX | 3 × 10 = 30 |
I | 1 |
LXXXI | 81 |
Every symbol here is written in descending order and simply added together — no subtractive pairs are involved.
Nearby numbers
| Number | Roman numeral |
|---|---|
| 76 | LXXVI |
| 77 | LXXVII |
| 78 | LXXVIII |
| 79 | LXXIX |
| 80 | LXXX |
| 81 | LXXXI |
| 82 | LXXXII |
| 83 | LXXXIII |
| 84 | LXXXIV |
| 85 | LXXXV |
| 86 | LXXXVI |
The seven symbols
I | 1 | C | 100 |
V | 5 | D | 500 |
X | 10 | M | 1,000 |
L | 50 |
81 in other notations
| Roman | LXXXI |
| Binary | 1010001 |
| Hexadecimal | 51 |
| Octal | 121 |
| Written out | eighty-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 81:
L = 50 remaining: 31
3 × X = 30 remaining: 1
I = 1 remaining: 0The result reads LXXXI — 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 81 in Roman numerals?
LXXXI
How do you read LXXXI?
Work left to right, adding each symbol — except where a smaller symbol precedes a larger one, in which case it is subtracted. L is 50, XXX is 30, I is 1, giving 81 in total.
How do you write 81 in words?
eighty-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.