math
posted by david .
It is estimated that one third of one per cent of the Earth’s surface receives more energy from the sun than the total projected needs for the year 2014. Assuming the Earth’s surface to be 1.97 x 108 square miles. Find the area in acres.

0.01/3 * 1.97*10^8 mi^2 * 640acre/mi^2 = 4.2*10^8 acres