I just memorize 3.14159265 since the following digits are 35 (I'll never be able to un-remember this now) my error is like 1 in 10e9 and I've never used Pi in any context where that was even close to mattering. The most accurate calculations I ever had to do in software needed about 1um in a meter accuracy... so I have 3 orders of magnitude of accuracy margin. Never tried to get a spaceship to the edge of the universe with any accuracy though ;) I prefer to use built in values usually since they are typically accurate to the full precision but on platforms where for some reason that wasn't available... Of course the specific calculations you're doing also matter since small errors can accumulate to larger ones if you're not careful...
Another personal anecdote is that in a company that shall remain unnamed we used to have a Pi from memory competition every Pi day (3/14). The president of the company always won. I don't recall how many digits he knew but it was some ridiculously high number (hundreds). I much prefer my family tradition of eating pie on Pi days.
Another personal anecdote is that in a company that shall remain unnamed we used to have a Pi from memory competition every Pi day (3/14). The president of the company always won. I don't recall how many digits he knew but it was some ridiculously high number (hundreds). I much prefer my family tradition of eating pie on Pi days.