# Definition:Golden Mean/Definition 2

## Definition

The golden mean is the unique positive real number $\phi$ satisfying:

$\phi = \dfrac {1 + \sqrt 5} 2$

## Decimal Expansion

The decimal expansion of the golden mean starts:

$\phi \approx 1 \cdotp 61803 \, 39887 \, 49894 \, 84820 \, 45868 \, 34365 \, 63811 \, 77203 \, 09179 \, 80576 \ldots$