# Mathematician:Leonardo Fibonacci

## Contents

## Mathematician

Italian mathematician.

One of the most important figures in the history of the development of mathematics.

Wrote the highly influential and important *Liber Abaci* in which he discussed the Hindu-Arabic number system and its practical applications.

Most famous for the Fibonacci numbers. The number sequence itself was known to Indian mathematicians as early as the 6th century, but it was Fibonacci's *Liber Abaci* which made them well-known throughout Europe.

## Nationality

Italian

## History

- Born: c. 1170
- Died: c. 1250

## Theorems and Definitions

- Fibonacci numbers
- Brahmagupta-Fibonacci Identity (with Brahmagupta)
- Practical Number (discussed at length in
*Liber Abaci*)

### Concepts derived from Fibonacci numbers

Results named for **Leonardo Fibonacci** can be found here.

Definitions of concepts named for **Leonardo Fibonacci** can be found here.

## Publications

- 1202:
*Liber Abaci*(*Book of Abacus*or*Book of Calculation*) which introduced the Arabic numerals to the Western world. Sometimes (possibly erroneously) called*Liber Abbaci*. - 1220:
*Practica Geometriae*, a compendium on geometry and trigonometry. - 1225:
*Flos*, solutions to problems posed by a friend of his,**Johannes of Palermo**. - 1225:
*Liber quadratorum*(*The Book of Squares*) on Diophantine equations, in which in particular the Brahmagupta-Fibonacci Identity is discussed. -
*Di minor guisa*, on commercial arithmetic (lost) - A commentary on Book X of Euclid's
*The Elements*(lost)

## Also known as

**Leonardo Fibonacci** also known as **Leonardo of Pisa**, **Leonardo Pisano**, **Leonardo Bonacci** or usually just **Fibonacci**.

The name **Fibonacci** comes (posthumously) from **filius Bonacci**, that is: **son of Bonacci** (his father was nicknamed **Bonacci**, meaning **good-natured** or **simpleton**). These were the days before official surnames.

An ironic soubriquet.

## Linguistic Note

**Fibonacci** is an Italian surname whose pronunciation is something like ** Fib-bo-nat-chi**, or

**, according to taste.**

*Fib*-bo-*nar*-chiAvoid pronouncing it ** Fie-bo-nac-ky**.

## Sources

- John J. O'Connor and Edmund F. Robertson: "Leonardo Fibonacci": MacTutor History of Mathematics archive

- 1997: David Wells:
*Curious and Interesting Numbers*(2nd ed.) ... (previous) ... (next): A List of Mathematicians in Chronological Sequence - 1997: David Wells:
*Curious and Interesting Numbers*(2nd ed.) ... (previous) ... (next): $0$ Zero - 2008: Ian Stewart:
*Taming the Infinite*... (previous) ... (next): Chapter $3$: Notations and Numbers