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Mastering Roman Numerals: Converter & Guide

The Roman Numerals Converter is a tool designed to translate numbers between the standard Arabic numeral system (0, 1, 2, ...) and the ancient Roman numeral system (I, V, X, L, C, D, M). This calculator supports conversions for numbers typically from 1 to 3999, which is the common range for standard Roman numeral notation.

📜 How to Use the Converter

Using the converter is simple:

1. Select Conversion Mode: Choose "Number to Roman" to convert an Arabic numeral to a Roman numeral, or "Roman to Number" to convert a Roman numeral to an Arabic numeral.
2. Enter Value:
   • If converting to Roman: Enter an integer between 1 and 3999.
   • If converting to Arabic: Enter a valid Roman numeral (e.g., MMXIV, CIX).
3. Click "Convert": The calculator will perform the conversion.
4. View Result: The converted value will be displayed, along with a step-by-step explanation of the conversion process if applicable.

Understanding Roman Numerals

The Roman numeral system uses combinations of letters from the Latin alphabet to signify values. The standard symbols are:

Rules for Forming Roman Numerals:

• Repetition: A symbol can be repeated up to three times in a row to multiply its value (e.g., III = 3, XXX = 30, CCC = 300, MMM = 3000). V, L, and D are never repeated.
• Addition: If a symbol of smaller value follows a symbol of greater or equal value, their values are added (e.g., VI = 5 + 1 = 6, LX = 50 + 10 = 60, MC = 1000 + 100 = 1100).
• Subtraction (Subtractive Notation):
  • I before V or X: IV = 4 (5-1), IX = 9 (10-1)
  • X before L or C: XL = 40 (50-10), XC = 90 (100-10)
  • C before D or M: CD = 400 (500-100), CM = 900 (1000-100)
  Only one smaller value symbol can be placed before a larger value symbol for subtraction. The subtractive symbol must be I, X, or C.
• Largest to Smallest: Generally, symbols are placed from left to right in order of value, starting with the largest.

💡 Frequently Asked Questions (FAQ)

Why is the conversion limited to 3999?

The standard Roman numeral system does not have a conventional way to represent numbers of 4000 or greater. While historical notations like a bar over a numeral (V̅ for 5000) existed, they weren't standardized. This calculator adheres to the most common, modern rules.

Why can't you write 'IIII' for 4?

The standard rules of Roman numerals state that a symbol should not be repeated more than three times in a row. To represent 4, the subtractive principle is used: IV, meaning 'one less than five'.