Fibonacci ( born around the year 1170 , died around 1250 ) , full name Leonardo Pisano Bigollo , was an Italian mathematician and among the most distinctive mathematicians in the Western world of the Middle Ages . Leonardo Pisano Bigollo ( c. 1170 â `` c. 1250 ) also known as Leonardo of Pisa , Leonardo Pisano , Leonardo Bonacci , Leonardo Fibonacci , or , most commonly , simply Fibonacci , was an Italian mathematician , considered by some `` the most talented western mathematician of the Middle Ages . ''