This number is equal to about 1.61803398875, also known as the golden ratio or divine proportion. It is essential to geometry ad can be expressed as a ratio of a regular pentagon’s diagonal to the length of a side.

This number has always fascinated mathematicians, astronomers, biologists and artists, since the ratio is representing is thought to have aesthetic appeal.

In US, Illinois, the German-American architect Mies van der Rohe’s house Farnsworth House is said to be build according to φ