So called after Leonardo Fibonacci who first described the sequence, numbers made by adding the previous two:

0,1,1,2,3,5,8,13,21,34,55

If squares are arranged as below a spiral can be drawn by connecting the diagonal corners of each to form a Fibonacci Spiral

Seem familiar?

This shape appears in nature time after time:

snail shells

Pine cones

sunflower seeds

pine apples

breaking waves

hurricanes

galaxies

φ This is “phi” the Greek letter given to the golden ratio the ratio of any pair of Fibonacci numbers for example if we divide 5 by 3 we get 1.66666666

8 divided by 5 we get 1.6

13 divided by 8 we get 1.625

all are roughly the same 1.6 if you average them you get the so called golden ratio phi 1.618

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