diameter=16 so divide by 2 to find radius
16/2=8=r
area of circle= pi*r^2
area of circle= pi*8^2
area of circle=64pi
now either leave it as an exact answer (64pi u^2) or convert it to a decimal and then round
201.06192983
round to nearest tenth= 201.1 u^2
or round to the nearest hundreth=201.06 u^2
