In medieval Europe doing business requires an abacus, basic arithmetic was nearly impossible without it. Arithmetic with roman numerals was done by counting each of the individual symbols on the abacus. Thus merchants and bankers needed to be skilled using an abacus or hired a skilled abacist. Business, commerce and mathematics was slow, inefficient and costly. To Leonardo of Pisa, there was a better way.

Leonardo of Pisa (1170 -1240) better known as Fibonacci, travels throughout the Mediterranean to study with Arab mathematicians. The Arabs had their own number system that did not require an abacus. With 10 symbols, 0-9, they could represent large numbers and were easier to handle. Arab traders, merchants and bankers did not need to be skilled at using an abacus or hire abacists, they only needed something to write on. Seeing the benefit, Fibonacci returns to Pisa in 1202 with his book “Liber Abaci”, the first book in western Europe to use the Arabic number system.

In the “Liber Abaci”, the book of calculations, Fibonacci details how the Arabic number system can be applied to business. He shows how businessmen can quickly add numbers, calculate interest rates and convert currencies. He shows how this number system can be applied to well known mathematical theorems and formulas. He also shows how it can easily compute a series of numbers which would bear his nickname: the Fibonacci number sequence.

His work revolutionizes mathematics and commerce in Europe as many began adopting and promoting the Arabic number system over the Roman Numerals. Unfortunately due to the cost of paper, adoption of the Arabic Number system wasn’t wide spread until the late 16th century.

For his work on bringing the Arabic number system to Europe, Fibonacci not only proves commerce but greatly impacts western thought.

**Sources Used:**

- http://commons.wikimedia.org/wiki/File:Fibonacci.jpg#mediaviewer/File:Fibonacci.jpg
- http://www.nndb.com/people/922/000095637/
- http://www-history.mcs.st-and.ac.uk/Biographies/Fibonacci.html
- http://www.math.udel.edu/~pelesko/Teaching/Math308_Spring_2006/carlypresentation.pdf
- http://www.archimedes-lab.org/numeral.html