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Roman Numeral

Convert between Decimal and Roman Numerals, and compute Roman Numeral arithmetic.

Roman Numeral Engine & Converter Handbook

Mathematical Principles & Theorems

Roman numeral notation represents integers using additive and subtractive Latin glyph combinations: Primary symbols I (1), V (5), X (10), L (50), C (100), D (500), M (1000). Subtractive pairs: IV (4), IX (9), XL (40), XC (90), CD (400), CM (900). For large values \(\ge 4000\), Vinculum horizontal bar notation multiplies glyph values by 1,000 (\(\overline{\text{V}} = 5,000, \overline{\text{X}} = 10,000, \overline{\text{M}} = 1,000,000\)), supporting numbers up to 3,999,999.

Operating Instructions

  • Enter a decimal integer or Roman numeral string in the converter inputs.
  • Click Convert to perform bidirectional translation with strict syntax validation.
  • Perform direct Roman arithmetic operations (Addition, Subtraction, Multiplication).
  • Review the decomposition breakdown table showing subtractive and additive token values.

Parameters

Calculator Params

Conversion Results

Roman Numeral -
Decimal Number -

Calculation Results

Result (Roman) -
Result (Decimal) -