# 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 $6$th 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) (also known as Diophantus's Identity)
- Practical Number (discussed at length in
*Liber Abaci*)

### Concepts derived from Fibonacci numbers

- Fibonacci Polynomial
- Fibonacci Prime
- Fibonacci String, also known as a Fibonacci Word
- Fibonacci Number System
- Fibonacci Nim
- Reciprocal Fibonacci Constant
- Pisano Period

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)

## Critical View

*Fibonacci was by far the greatest European mathematician of the Middle Ages.*

## 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

- 1986: David Wells:
*Curious and Interesting Numbers*... (previous) ... (next): A List of Mathematicians in Chronological Sequence - 1986: David Wells:
*Curious and Interesting Numbers*... (previous) ... (next): $0$ Zero - 1997: Donald E. Knuth:
*The Art of Computer Programming: Volume 1: Fundamental Algorithms*(3rd ed.) ... (previous) ... (next): $\S 1.2.8$: Fibonacci Numbers - 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