01 What are Roman Numbers?

Roman numerals – Wikipedia

Roman numerals are the numerical signs of a numerical script that originated in Roman antiquity and is still in use today for numbers and special purposes. In the form used today, the Latin letters I, V, X, L, C, D, and M are used as number signs for writing the natural numbers.


It is an additive number script, with a supplementary rule for the subtractive writing of certain numbers, but without a place value system and without a character for zero.

It is based on a number system with the base numbers 5 and 10.

Simple conversion – additive Notation

To convert to a Roman numeral without the subtraction rule described below, start with the large Roman numerals and subtract their value as often as possible from the number to be converted, noting the Roman numerals as you do so.

This will automatically sort the digits by size:


To add back such a roman number, only the values of the individual number signs have to be added.

Subtractive notation

The subtraction rule is a common, abbreviated notation that avoids writing four identical number signs in direct succession.

The number signs I, X and C may be placed in front of one of their two next larger number signs and are then to be subtracted in their number value from its value:

I before V or X: IV (4), IX (9)
X before L or C: XL (40), XC (90)
C before D or M: CD (400), CM (900)

Functions the GC Wizard provides

The GC Wizard offers the following functions for Roman numerals:

  • Conversion of Roman numerals
  • Search Roman numerals in texts – Chronogram