Liber Abaci (1202) is an historic book on arithmetic by Leonardo of Pisa, known later by his nickname Fibonacci. Its title has two common translations - The Book of the Abacus or The Book of Calculation. In this work, Fibonacci introduced to Europe Hindu-Arabic numerals, also known as the decimal system, which he had learned by studying with Arabs while living in North Africa with his father, Guilielmo, who wished for him to become a merchant.

Liber Abaci was not the first Western book to describe Hindu-Arabic numerals, but by addressing tradesmen rather than academics, it was the book that convinced the public of the superiority of the new system. The first section introduces the Hindu-Arabic numeral system. The second section presents examples from commerce, such as conversions of currency and measurements, and calculations of profit and interest. The third section discusses a number of mathematical problems. One example, describing the growth of a population of rabbits, was the origin of the Fibonacci sequence for which the author is most famous today. The fourth section derives approximations, both numerical and geometrical, of irrational numbers such as square roots. The book also includes Euclidean geometric proofs and a study of simultaneous linear equations.

Further reading

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• An English translation by L. E. Sigler (ISBN 0387954198)

• A German translation and analysis by Heinz Leuneburg,

"Leonardo Pisani Liber Abbaci Oder Lesevergneugen eines Mathematikers" ISBN 3-411-15462-4

13th century books

Liber abaci | Liber abbaci