1,618... The golden ratio

It is an irrational algebraic number (non-periodic infinite decimal) that has many interesting properties, which was discovered in antiquity, not "unity" but as a relationship or ratio between line segments. This ratio is found both in geometric figures as in nature. It can be found in geometric elements in the veins of the leaves of some trees in the thickness of the branches, in the shell of a snail, in florets of sunflowers, etc.. 

Additional aesthetic character attributed to objects whose actions saved the golden ratio. Some even believe that has a mystical significance. Throughout history, it has attributed its inclusion in the design of various works of architecture and other arts, although some of these cases have been questioned by scholars of mathematics and art.