Fibonacci Numbers

A number sequence discovered by a thirteenth century Italian mathematician Leonardo Fibonacci (ca 1170-1250), who introduced Arabic numbers to Europe, in which the sum of any two consecutive numbers equals the next highest number – i.e., following this sequence: 1, 1, 2, 3, 5, 8, 13, 21, 34, 55 and so on. The ratio of any number to its next highest number approaches 0.618 after the first four numbers. These numbers are used by technical analysts to determine price objectives from percentage retracements.

Source: Commodity Futures Trading Commission