[fourier_mode]

I would never get used to how to remember the diameter of the earth. Now all I need to remember is how many km's are there in a nautical mile, get the length of the equator and divide it by pi. i.e. (360 x 60 x 1.85/3.14)

[reacweb]

The perimeter is 40,000 km. You just need to learn pi ;-)

[astazangasta]

24901.5 mi is the number i memorized for circumference as a wee bairn, before i knew about oblate eccentricity.