What is so special about the number $\pi$? There are many more interesting constants, such as
e, $\gamma, \sqrt{2}$ or the catalanian number.
$\pi$ has been calculated to more digits than any other irrational number.
$\pi$ is the only number used in memory contests. There is even a pi-day, the 14th March.
Is there any reason for that ?
Apparently because is the oldest one! It is 2500 years old!