What number is the golden ratio?
The golden ratio, or golden mean, or phi, is about
1.618033989.
The golden ratio is the ratio of two quantities such that the
ratio of the sum to the larger is the same as the ratio of the
larger to the smaller.
If the two quantities are a and b, their ratio is golden if a
> b and (a+b)/a = a/b.
This ratio is known as phi, with a value of about 1.618033989.
Exactly, the ratio is (1 + square root(5))/2.