1cm=10,000m Therefore, 1 cm 2 = ( 10 , 000 m ) 2 = 100 , 000 , 000 m 2 1cm 2 =(10,000m) 2 =100,000,000m 2 . Thus, 12 cm 2 = 12 100 , 000 , 000 m 2 = 1 , 200 , 000 , 000 m 2 12cm 2 =12100,000,000m 2 =1,200,000,000m 2 . Calculate the area of one cell: The diameter of one cell is 12 m. The radius r is half of the diameter: = 12 m 2 = 6 m r= 2 12m =6m. The area A of one cell is given by the formula for the area of a circle, = 2 A=r 2 : = ( 6 m ) 2 = 36 m 2 113.097 m 2 A=(6m) 2 =36m 2 113.097m 2 . Calculate the number of cells needed: The number of cells needed is the total surface area divided by the area of one cell: Numberofcells = 1 , 200 , 000 , 000 m 2 113.097 m 2 10 , 609 , 082.56 Numberofcells= 113.097m 2 1,200,000,000m 2 10,609,082.56