Golden Ratio
#Math
$\displaystyle \phi= \frac{1+\sqrt{ 5 }}{2}$
Also related to how $\displaystyle \frac{1}{\frac{1}{\frac{1}{\frac{1}{\frac{1}{\frac{1}{\frac{1}{\frac{1}{\frac{1}{\frac{1}{x+1}+1}+1}+1}+1}+1}+1}+1}+1}+1}$ is approximately $\displaystyle \frac{\sqrt{ 5 }-1}{2}$ for any $\displaystyle x$