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Roman Numeral Converter

Math

Convert between Arabic numbers and Roman numerals. Learn about the ancient Roman numbering system, its rules, and modern applications.

Number Converter

Quick Examples

🏛️ Conversion Results

Arabic Number
Modern decimal system
42
Roman Numeral
Ancient Roman system
XLII

📜 Roman Numeral Symbols

I
One
1
V
Five
5
X
Ten
10
L
Fifty
50
C
One Hundred
100
D
Five Hundred
500
M
One Thousand
1000

📐 Subtractive Notation Rules

Valid Subtractive Combinations

CM
1000 - 100
900
CD
500 - 100
400
XC
100 - 10
90
XL
50 - 10
40
IX
10 - 1
9
IV
5 - 1
4

Subtractive Rules

  • • Only I, X, and C can be subtracted
  • • I can only be subtracted from V and X
  • • X can only be subtracted from L and C
  • • C can only be subtracted from D and M
  • • Only one smaller numeral can precede a larger one
  • • The smaller numeral must be at least 1/10 of the larger

🏛️ History of Roman Numerals

Ancient Origins

Roman numerals evolved from Etruscan numerals around the 7th century BC. The system was used throughout the Roman Empire for trade, administration, and monumental inscriptions.

  • • 7th century BC: Adopted from Etruscan system
  • • Roman Empire: Standard for official documents
  • • Medieval period: Used alongside Arabic numerals
  • • Renaissance: Continued use in formal contexts

Symbol Evolution

The symbols we use today evolved from ancient hand gestures and tally marks. Each symbol has a fascinating origin story rooted in practical counting methods.

  • • I: Single tally mark or finger
  • • V: Open hand (5 fingers)
  • • X: Two hands crossed (10 fingers)
  • • C: From Latin “centum” (hundred)
  • • M: From Latin “mille” (thousand)

🌟 Modern Uses of Roman Numerals

Entertainment

  • • Movie sequels (Rocky IV)
  • • Super Bowl numbering
  • • Book chapters
  • • Video game titles

Formal Documents

  • • Copyright dates
  • • Building cornerstones
  • • Legal documents
  • • Academic papers

Design & Art

  • • Clock faces
  • • Architectural elements
  • • Luxury branding
  • • Tattoos and jewelry

💡 Conversion Tips & Tricks

Reading Roman Numerals

  • • Read from left to right
  • • Add values when symbols decrease or stay same
  • • Subtract when a smaller symbol precedes larger
  • • Look for subtractive combinations first

Writing Roman Numerals

  • • Start with largest values first
  • • Use subtractive notation when appropriate
  • • Never repeat a symbol more than 3 times
  • • Use standard combinations (IV not IIII)