Fibonacci

Leonardo Bonacci, known as Fibonacci, was an Italian mathematician who lived around the year 1200. He came from the Republic of Pisa.

Fibonacci helped bring new numbers to Europe. These numbers are called the Indo–Arabic numeral system. He wrote a famous book in 1202 called Liber Abaci. This book showed how to use these numbers for everyday math.

In his book, Fibonacci used a special list of numbers called the Fibonacci numbers. These numbers start with 0 and 1. Each new number is the sum of the two before it, like 0, 1, 1, 2, 3, 5, and so on.

Biography

Fibonacci was born around 1170 in Bugia, which is now Béjaïa in Algeria. As a young boy, he traveled with his father, a merchant. He learned about numbers using the Hindu–Arabic numeral system. This system was easier for calculations than the Roman numerals used in Europe at the time.

Fibonacci traveled around the Mediterranean and learned from many merchants. In 1202, he wrote a book called Liber Abaci. This book helped introduce the Hindu-Arabic numerals to Europe. Later, he advised Emperor Frederick II on mathematics. He was honored by the Republic of Pisa for his work.

Liber Abaci

Main article: Liber Abaci

In the Liber Abaci (1202), Fibonacci introduced a new way of writing numbers called the modus Indorum, or the method of the Indians. Today, we call this the Hindu–Arabic numeral system. This system uses ten digits, including a zero, and positional notation. The book showed how useful these numbers were for everyday tasks like keeping track of money, changing weights and measures, and calculating interest. This made business much easier and helped grow banking and accounting in Europe.

Although the original 1202 manuscript is lost, a copy from 1228 shows how Fibonacci compared these new numbers to older ones like Roman numerals. The book also taught how to use these numbers for tasks such as changing currencies and figuring out profits, as well as discussing special kinds of numbers like irrational numbers and prime numbers.

Fibonacci sequence

Fibonacci solved a problem about how rabbit families grow. This led to a special list of numbers called Fibonacci numbers. In this list, each number is the sum of the two numbers before it. Fibonacci started his list with 1, 2, 3, and went up to the thirteenth number, which is 233. Indian mathematicians had used this idea even earlier, way back in the sixth century.

Legacy

In the 19th century, a statue of Fibonacci was placed in Pisa. Today, you can see it in the western gallery of the Camposanto, a historical cemetery on the Piazza dei Miracoli.

Many math ideas are named after Fibonacci because they connect to the Fibonacci numbers. These include the Brahmagupta–Fibonacci identity, the Fibonacci search technique, and the Pisano period. Beyond math, Fibonacci’s name is also used for things like the asteroid 6765 Fibonacci and the art rock band The Fibonaccis.

Works

Fibonacci wrote several important books. His most famous book is Liber Abaci. It was written in 1202 and helped people learn calculations. Another book, Practica Geometriae, came out in 1220. It taught geometry skills for measuring land and objects. In 1225, he wrote Flos, which solved many math problems. He also wrote Liber quadratorum. This book talked about special math equations. It was for Emperor Frederick II. Sadly, two of his other books, Di minor guisa and a Commentary on Book X of Euclid's Elements, are lost today.