Leonardo Fibonacci (1170-1240) may have been the most talented Western mathematician of the Middle Ages. He was born and raised in the Italian city-state Pisa. As a boy, he traveled the Mediterranean region with his father and brought back new knowledge that would change math and science forever: the Hindu-Arabic numbers.

### Islam

When Fibonacci was born, an Islamic Empire controlled large parts of the Mediterranean, having taken over sections of the former Roman Empire. The Arab society gathered and concentrated knowledge in what is known as the Golden Age of Islam.

### Numbers

In Europe, people were only accustomed to the Roman number system, which was hard to master for calculations. Hindu-Arabic numbers, which Fibonacci brought back from his travels, are still used in the modern world; they include the digits 1, 2, 3, 4, 5, 6, 7, 8, 9, and 0.

Roman numerals, on the other hand, used letters of the alphabet to represent different units. For example:

I = 1

V = 5

X = 10

C = 100

M = 1,000

The Hindu-Arabic number system had two features that made it extremely easy to use. First, it included the number zero. Second, it only had ten different symbols that were reused and given new values *depending on their position* in the number.

### Liber Abaci

*Liber Abaci*.

He included a description of the Hindu-Arabic numbers and gave many practical examples of how they could be used for accounting by merchants. With math more accessible, people could start banks and trading companies. It created economic growth in Europe.

### The Scientific Revolution

By the 16th century, mathematics was so well-developed that scientists could use it to study the natural world. People like Nicolaus Copernicus, Tycho Brahe, Johannes Kepler, Galileo Galilei, and Isaac Newton used this tool to formulate theories about the motions of the planets.

Without the Hindu-Arabic numerals, it would have been near impossible to make this progress.