Leonardo Da Pisa, Or Leonardo Bonaeci Or, Bonaceio, an Italian mathematician, born in Pisa about 1170; the year of his death is unknown. He is also called Fibonacci, an abbreviation of Filius Bonaeci. Little is known of him beyond what can be gathered from his mathematical works. His father placed him when very young in charge of a master who taught him the Arabic (or, as he calls it, the Indian) system of arithmetic, and he seems to have devoted the greater part of his life to the study of that science. Though the Arabic system was known in Europe previous to the time of Bonaeci, yet he greatly extended that knowledge, and according to some he was the first to introduce algebra into Europe. He travelled in Egypt, Syria, and other countries, for the purpose of learning the different systems of arithmetic in use, and came to the conclusion that the Arabic or Indian method surpassed all others. His principal work is Liber Abaci, the word abacus, the name of a well known instrument used in calculation, being employed by him, in accordance with the custom of his time, to denote arithmetic in its most general sense. He was also the author of works on the Dio-phantine analysis and geometry, all of which give evidence of great mathematical genius.

A splendid edition of the Liber. Abaci was published at Rome in 1857, edited by B. Bon-compagni, to whom the modern world is indebted for its knowledge of the works of Bonacci.