Question 451294
If the diameter is 18 cm, then the radius is {{{r=18/2=9}}} cm.



{{{S=4pi*r^2}}} Start with the surface area of a sphere formula.



{{{S=4pi*(9)^2}}} Plug in {{{r=9}}}.



{{{S=4(3.14159265)(9)^2}}} Replace {{{pi}}} with {{{3.14159265}}} (note: Use more digits of {{{pi}}} to get better accuracy).



{{{S=4(3.14159265)(81)}}} Square {{{9}}} to get {{{81}}}.



{{{S=4(254.46900465)}}} Multiply {{{3.14159265}}} and {{{81}}} to get {{{254.46900465}}}.



{{{S=1017.8760186}}} Multiply {{{4}}} and {{{254.46900465}}} to get {{{1017.8760186}}}.



{{{S=1017.88}}} Round to the nearest hundredth.



So the surface area of a sphere with a diameter of {{{18}}} cm is approximately {{{1017.88}}} square cm.



I'll let you do the conversion to square meters.