ROMAN NUMERAL VALIDATOR

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ROMAN NUMERAL
VALIDATOR

Check if Roman numerals are valid and follow proper construction rules. Detect common errors and learn the correct format.

TEST EXAMPLES

XIV

Valid Roman numeral

IIIIX

Invalid pattern (should be XIV)

VV

V cannot be repeated

IL

I cannot subtract from L

MCMXC

Valid complex numeral (1990)

MMMCMXCIX

Valid maximum (3999)

VALIDATION RULES

REPETITION RULES

  • • I, X, C, M can repeat up to 3 times
  • • V, L, D cannot be repeated
  • • Use subtraction instead of 4+ repetitions

SUBTRACTION RULES

  • • I can subtract from V and X only
  • • X can subtract from L and C only
  • • C can subtract from D and M only
  • • Only one smaller numeral before larger

COMMON MISTAKES

  • • IIII → should be IV
  • • IIIIX → should be XIV
  • • VV → should be X
  • • IL → should be XLIX

VALID CHARACTERS

  • • I (1), V (5), X (10)
  • • L (50), C (100), D (500)
  • • M (1000)
  • • Case insensitive