This KS2 Maths article explains how Roman numerals uses letters instead of numbers to represent values.

Recap: What Are Roman Numerals? Before we begin figuring out how to add and subtract Roman style, let’s recap how the Roman numeral system that we learned about last time works.

Before the 13th century Europeans used Roman numerals to do arithmetic. Leonardo of Pisa, better known today as Fibonacci, is largely responsible for the adoption of the Hindu–Arabic numeral ...

Roman numerals were fine for adding and subtracting. Fibonacci saw that complex math required a better system.

The math to get 59 in Roman numerals is fairly simple: L = 50 and IX = 9. Therefore, LIX = 59. Roman numerals use different combinations of the same letters to create numbers.

In 1202 Leonardo da Pisa (aka Fibonacci) taught Western Europe how to do arithmetic with Arabic numerals. In Man of Numbers: Fibonacci's Arithmetic Revolution, Keith Devlin describes how basic ...