Leonardo Fibonacci
Leonardo Fibonacci, Italian mathematician (c1170- c1250), coloured artwork. Fibonacci introduced the 'Arabian' numeral system to Europe, through his Book of the Abacus (1202). He also discovered a sequence of numbers in which each number is the sum of the previous two: 1, 1, 2, 3, 5, 8, 13, and so on. This was named the Fibonacci series. This series is often found in nature, for example in the patterns of leaf growth.