At school, I somehow talked myself into a dumb competition with my math geek about memorizing digits of pi.

I won, with 35 digits memorized (he gave up early; that's also around where the first '0' occurs in pi).

I don't miss any opportunities to test that I still remember them correctly, to this day. ;)

I had a hard time getting past the "399" out about 43. I wanted to round it to "4".

But these days I would rather memorize tau:

  6.28318530717958647692528676655900576839433879875021

It has that "00" at 27 digits in that must be got past.