To carry out their calculations, merchants in the early 13th century used an abacus or a system called finger reckoning. Commerce changed when Leonardo of Pisa — known today as Fibonacci ...

If you think Fibonacci was just a crazy Italian mathematician, consider this: The May 2 high at 1,370 and the June 16 low at 1,258 occurred right.

In 1202 Leonardo da Pisa (aka Fibonacci) taught Western Europe how to do arithmetic with Arabic numerals. In Man of Numbers: Fibonacci's Arithmetic Revolution, Keith Devlin describes how basic ...