fibonacci sequence

A specific sequence of numbers (1, 1, 2, 3, 5, 8, 13, 21, 34…) in which the next number in the sequence is derived by adding together the previous two numbers in the sequence. A modified version of the Fibonacci Sequence is one common sequences used when performing relative size estimations of product backlog items. Another sequence that some teams use is powers of two (e.g., 1, 2, 4, 8, 16, 32…) See Planning Poker.