if d=2.1 cm
then c= (22)(2.1)/7
c=10.06 cm rounded off.
c=14.143 cm rounded off
"22/7 is not exactly a pi" even if you ask your instructor..
22/7 is not the final answer so we can't round off it. because your answer might be wrong..
the pi in the formula in getting circumference is a constant so we cant replace with the other constant..