20 pi
Circumference is Diameter*pi so if it uses that either use 3.14 to substitute for pi or use the real number.
20 pi
Okay, so do 20*pi and what you get from that is 62.8318530718(that's as far as my calculator goes...)
If you want to use 3.14 you get 62.8. So in reality it's 20 pi.