Roman Numeral Converter
Convert Roman numerals to decimal numbers and decimal numbers to Roman numerals.
Conversion
Roman Numerals System
Roman numerals are a numeral system that originated in ancient Rome. They are based on seven symbols, each with a fixed integer value.
Basic Symbols and Values:
- I = 1
- V = 5
- X = 10
- L = 50
- C = 100
- D = 500
- M = 1000
Rules for Formation:
- Repetition: A numeral repeated up to three times adds its value (e.g., III = 3, XXX = 30).
- Addition: A smaller numeral placed after a larger numeral is added to the larger numeral (e.g., VI = 5 + 1 = 6, LX = 50 + 10 = 60).
- Subtraction: A smaller numeral placed before a larger numeral is subtracted from the larger numeral. This rule applies to only a few combinations: IV (4), IX (9), XL (40), XC (90), CD (400), CM (900).
- Order: Numerals are generally written from largest to smallest from left to right.
Roman Numeral Examples
| Decimal | Roman Numeral | Explanation |
|---|---|---|
| 1 | I | One |
| 4 | IV | Five minus one |
| 9 | IX | Ten minus one |
| 10 | X | Ten |
| 40 | XL | Fifty minus ten |
| 90 | XC | Hundred minus ten |
| 100 | C | Hundred |
| 400 | CD | Five hundred minus hundred |
| 900 | CM | Thousand minus hundred |
| 1000 | M | Thousand |
| 1994 | MCMXCIV | 1000 + (1000-100) + (100-10) + (5-1) |
Frequently Asked Questions
What are Roman numerals?
Roman numerals are a numeral system that originated in ancient Rome and remained the usual way of writing numbers throughout Europe well into the Late Middle Ages. They are based on seven symbols: I, V, X, L, C, D, and M.
What are the basic rules for Roman numerals?
1. Repetition: A numeral repeated up to three times adds its value (e.g., III = 3). 2. Addition: A smaller numeral after a larger one is added (e.g., VI = 6). 3. Subtraction: A smaller numeral before a larger one is subtracted (e.g., IV = 4). 4. Order: Numerals are generally written from largest to smallest.
What is the largest number that can be represented by standard Roman numerals?
The largest number that can be represented by standard Roman numerals without using vinculum (a bar over a numeral to multiply by 1,000) is 3,999 (MMMCMXCIX).