Fibonacci sequence, that list of numbers where the next digit is given by adding the previous two. It goes 1, 1, 2, 3, 5, 8, 13 and so on. But here’s something strange: work out the ratio of each number and its predecessor, and you start edging towards a specific number. Its first few digits are 1.618.

Fibonacci sequence, that list of numbers where the next digit is given by adding the previous two. It goes 1, 1, 2, 3, 5, 8, 13 and so on. But here’s something strange: work out the ratio of each number and its predecessor, and you start edging towards a specific number. Its first few digits are 1.618.This mysterious beast is the golden ratio, and it crops up a lot.