The Golden Mean is represented by the Greek letter phi. Phi is one of those mysterious natural numbers that seem to arise out of the basic structure of our cosmos. Phi appears clearly and regularly in the realm of things that grow and unfold in steps, and that includes living things.
The decimal representation of phi is 1.6180339887499…
The Golden Ratio describes the perfectly symmetrical relationship between two proportions.
The Golden ratio is a special number found by dividing a line into two parts so that the longer part divided by the smaller part is also equal to the whole length divided by the longer part. It is often symbolized using phi, after the 21st letter of the Greek alphabet. In an equation form, it looks like this:
a/b = (a+b)/a = 1.6180339887498948420 …
The Fibonacci series is if you start with the numbers 0 and 1, and make a list in which each new number is the sum of the previous two, you get a list like this:
0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, … to infinity–>
If you remove this square from the rectangle, you’ll be left with another, smaller Golden Rectangle. This could continue infinitely, like Fibonacci numbers – which work in reverse. (Adding a square equal to the length of the longest side of the rectangle gets you increasingly closer to a Golden Rectangle and the Golden Ratio.)