Leonardo Pisano Fibonacci
c. 1170 - c. 1250

Leonardo Fibonacci was an Italian mathematician, considered by some "the most talented western mathematician of the Middle Ages."

Fibonacci is best known to the modern world for the spreading of the Hindu-Arabic numeral system in Europe, primarily through the publication in the early 13th century of his Book of Calculation, the Liber Abaci; and for a number sequence named after him known as the Fibonacci numbers, which he did not discover but used as an example in the Liber Abaci.

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Fibonacci Biography  from Wikipedia