Leonardo Pisano Bigollo, more commonly known as Fibonacci was a great mathematician in the early 13^{th} century. He is most known for his famous number sequence, the Fibonacci sequence. This is a fantastic sequence and surprisingly has a connection with the golden rule. Although Leonardo is most commonly known for this, this is not his most influential and prominent work in mathematics. His most impactful work is used every day by millions of people around the world. He was the head honcho in spreading the Hindu-Arabic numeral system in Europe.

It is commonly believed that Fibonacci was born to a wealthy Italian merchant. His father directed a trading post in Bulgia. Leonardo would travel with his papa to help. It was during this time traveling with his father that he learned about Hindu-Arabic numeral system. After studying throughout the Mediterranean world, he returned to Europe, bringing with him Hindu-Arabic numeral system. Europe was still using Roman numerals at this time. He used his book, *Liber* *Abaci*, which literally means *Book of Calculation*, to help spread this numeral system.

Now Fibonacci’s claim to switch from Roman numeral system to Hindu-Arabic numeral system could have easy got him laughed straight out of Europe. He had to market this new system well if he didn’t want to look like a fool. He accomplished that through the use of his book previously mentioned. In his book he showed the simplicity in mathematical computations by applying this numeral system to commercial bookkeeping, conversion of weights and measurements, the calculation of interest, and changing money. Clearly working with his papa as a young boy had a large impact in his life and his knowledge in the market place helped create a strong foundation for this new numeral system to launch off of in Europe.

The aim of the book was to be able to do calculations without the assistance of an abacus. In laymen terms it was to make math easier and that exactly was Fibonacci did. His book can be broken into four sections. The first section he introduces the Hindu-Arabic numeral system. The second section gives practical examples, such as conversion of money and measurements, and calculations of profits and interest. The third section talks about several mathematical problems. One problem in this section was on the growth of a population of rabbits. This is the origin of the Fibonacci sequence. The fourth section derives approximations of irrational numbers such as square roots.

This book, I believe, put the study of mathematics into a theoretical incubator. Math from this point starts to progress in its discoveries because it allowed much more ease when doing complex math.

On a side note: 2002 marked the 800^{th} anniversary of Liber Abaci. It was published for the first time in modern English. The book, on Amazon.com, cost $70! Even though it is 800 years old, Liber Abaci was and still is extremely significant to the science of mathematics.