Roman numerals: I=1, V=5, X=10, L=50, C=100, D=500, M=1000. Subtractive notation: IV=4, IX=9, XL=40, XC=90, CD=400, CM=900. Maximum standard value: MMMCMXCIX = 3999. Addition: XIV + III = XVII (14+3=17).
How to Use
Enter Roman or Arabic numbers:
- Input: Roman or decimal
- Operation: +, −, ×
- Output: Both Roman and decimal
Roman Rules
- Larger before smaller = add
- Smaller before larger = subtract
- Max 3 of same symbol in a row
- Maximum value: 3999
Subtractive Pairs
IV=4, IX=9, XL=40, XC=90, CD=400, CM=900. Only I, X, C can precede larger values for subtraction.
Step-by-Step Instructions
- 1Enter first Roman numeral.
- 2Select operation.
- 3Enter second Roman numeral.
- 4View result in both formats.
- 5Try different operations.