Liber abaci: Indian numerals and Arabic algebra in a Latin book
A textbook of reckoning published in 1202 by Leonardo, a merchant of Pisa known as Fibonacci. As a boy he studied with Arab teachers in Bugia (Algeria), where his father worked at the customs house, and he brought back from there the Indian way of writing numbers with nine digits and a zero. The book shows how to add, multiply, divide, calculate interest, exchange coins and share a partnership's profit with this notation.
The second half of the book is algebra: equations and problems, many of them taken from al-Khwarizmi and al-Karaji. Fibonacci could read al-Khwarizmi in Latin translations made in Spain.
Before this book a European merchant calculated on the abacus and wrote in Roman numerals. After it, reckoning on paper became possible for anyone who learned a few rules, and the Italian 'abacus masters' turned those rules into a profession.
Why this date
reliable. The first version of the book is dated 1202; the surviving one is the second, of 1228.
What it grew from
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Positional decimal system and zero
prerequisite for · Confidence: high
The Liber abaci introduced the Hindu-Arabic place-valued decimal system and Arabic numerals into Europe; without them the book would not exist.
Link sources
- O'Connor J. J., Robertson E. F. «Leonardo Pisano Fibonacci», MacTutor History of Mathematics Verified 4 Oct 2026
The book, which went on to be widely copied and imitated, introduced the Hindu-Arabic place-valued decimal system and the use of Arabic numerals into Europe.
"Verified" means that on that day the quotation was found at the address given, word for word. No date means we have not been able to open the source yet, not that the quotation is wrong.
- O'Connor J. J., Robertson E. F. «Leonardo Pisano Fibonacci», MacTutor History of Mathematics Verified 4 Oct 2026
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Algebra as a distinct method
influenced · Confidence: high
The algebraic part of the Liber abaci is built on al-Khwarizmi's problems: the numerical examples are taken largely from his algebra and from al-Karaji.
Link sources
- Vogel K. «Fibonacci, Leonardo, or Leonardo of Pisa», Dictionary of Scientific Biography, vol. 4, New York: Scribner, 1971, encyclopedia.com (1971) Verified 4 Oct 2026
The numerical examples are taken largely from the algebra of al-Khw
- Karpinski L. C. «Robert of Chester's Latin Translation of the Algebra of al-Khowarizmi», New York: Macmillan, 1915, p. 34 (1915), 34 Verified 4 Oct 2026
Woepcke has shown that Leonard drew many of his problems from Al-Khowarizmi
"Verified" means that on that day the quotation was found at the address given, word for word. No date means we have not been able to open the source yet, not that the quotation is wrong.
- Vogel K. «Fibonacci, Leonardo, or Leonardo of Pisa», Dictionary of Scientific Biography, vol. 4, New York: Scribner, 1971, encyclopedia.com (1971) Verified 4 Oct 2026
Node sources
- Encyclopædia Britannica, 11- (1911), «Leonardo of Pisa» (M. Cantor), 16, Wikisource (1911), 454 Verified 4 Oct 2026
In 1202 he was again in Italy and published his great work, Liber abaci
"Verified" means that on that day the quotation was found at the address given, word for word. No date means we have not been able to open the source yet, not that the quotation is wrong.