**Leonard of Pisa** or **Fibonacci** played an important role in reviving ancient mathematics and made significant contributions of his own. *Liber abaci* introduced the Hindu-Arabic place-valued decimal system and the use of Arabic numerals into Europe.

- Fibonacci himself sometimes used the name Bigollo, which may mean good-for-nothing or a traveller.
- Fibonacci ended his travels around the year 1200 and at that time he returned to Pisa.
- Fibonacci lived in the days before printing, so his books were hand written and the only way to have a copy of one of his books was to have another hand-written copy made.
- One might have thought that at a time when Europe was little interested in scholarship, Fibonacci would have been largely ignored.
- Fibonacci was a contemporary of Jordanus but he was a far more sophisticated mathematician and his achievements were clearly recognised, although it was the practical applications rather than the abstract theorems that made him famous to his contemporaries.
- Frederick became aware of Fibonacci's work through the scholars at his court who had corresponded with Fibonacci since his return to Pisa around 1200.
- These scholars included Michael Scotus who was the court astrologer, Theodorus Physicus the court philosopher and Dominicus Hispanus who suggested to Frederick that he meet Fibonacci when Frederick's court met in Pisa around 1225.
- Johannes of Palermo, another member of Frederick II's court, presented a number of problems as challenges to the great mathematician Fibonacci.
- Three of these problems were solved by Fibonacci and he gives solutions in Flos Ⓣ(Flower) which he sent to Frederick II.
- After 1228 there is only one known document which refers to Fibonacci.
- This salary was given to Fibonacci in recognition for the services that he had given to the city, advising on matters of accounting and teaching the citizens.
- Liber abaci Ⓣ(Book of the abacus), published in 1202 after Fibonacci's return to Italy, was dedicated to Scotus.
- The book was based on the arithmetic and algebra that Fibonacci had accumulated during his travels.
- Certainly many of the problems that Fibonacci considers in Liber abaci Ⓣ(Book of the abacus) were similar to those appearing in Arab sources.
- (Fibonacci omitted the first term in Liber abaci Ⓣ(Book of the abacus)).
- The Fibonacci Quarterly is a modern journal devoted to studying mathematics related to this sequence.
- Fibonacci treats numbers such as √10 in the fourth section, both with rational approximations and with geometric constructions.
- Another of Fibonacci's books is Practica geometriae Ⓣ(Practical geometry) written in 1220 which is dedicated to Dominicus Hispanus whom we mentioned above.
- Fibonacci proves that the root of the equation is neither an integer nor a fraction, nor the square root of a fraction.
- Liber quadratorum, written in 1225, is Fibonacci's most impressive piece of work, although not the work for which he is most famous.
- the Liber quadratorum Ⓣ(Book of squares) alone ranks Fibonacci as the major contributor to number theory between Diophantus and the 17th -century French mathematician Pierre de Fermat.
- Fibonacci's influence was more limited than one might have hoped and apart from his role in spreading the use of the Hindu-Arabic numerals and his rabbit problem, Fibonacci's contribution to mathematics has been largely overlooked.
- Here Fibonacci became the teacher of the masters of computation and of the surveyors, as one learns from the "Summa" Ⓣ(Summary of arithmetic, geometry, proportion and proportionality) of Luca Pacioli ...
- Fibonacci was also the teacher of the "Cossists", who took their name from the word 'causa' which was first used in the West by Fibonacci in place of 'res' or 'radix'.
- Fibonacci's work in number theory was almost wholly ignored and virtually unknown during the Middle ages.

Born 1170, (probably) Pisa (now Italy). Died 1250, (possibly) Pisa (now Italy).

View full biography at MacTutor

Analysis, Ancient Arab, Ancient Babylonian, Ancient Indian, Geometry, Origin Italy, Number Theory, Puzzles And Problems, Special Numbers And Numerals

**O’Connor, John J; Robertson, Edmund F**: MacTutor History of Mathematics Archive