Question

To how many digits do you know `pi`?

Answer 1

For me, 3.141592653589793238462643383279502884197

Explanation:

I found it helpful to memorise a block of 5 or 6 digits at a time and make sure they had sunk in before memorising some more. I just stopped at some point and have not bothered to remember it further.

For real calculations, the approximation `355/113` is pretty good, being about `3.1415929`.