# What is the golden number in Mathematics?

Also called the golden ratio, divine ratio, or golden ratio, the golden number , designated by the Greek letter φ (phi), is defined as the only a / b relationship between two lengths a and b.

Like Pi, it is an irrational number that corresponds to the unique solution of the equation x ^{2} = x + 1.

Its origin dates back to the **pyramids of Cheops** and it would have been used first in geometry. The first text evoking the **golden number,** however, was written by Euclid in 300 BC, but it is Plato who seems to have dedicated a study in his own right. Later, it will be related to the **Fibonacci sequence** and will be synonymous with beauty in the 20th century.

It is used in **geometry** and **arithmetic,** but it is everywhere around us in nature, hence its connection to beauty and perfection. What is the golden number in Mathematics?