All 6 sides of a cube are squares and and all of these squares are of exactly the same size. Thus, find the area of a square of side 10 inches and then multiply your result by 6.
(10 in)^2 = 100 in^2; 6 times this is 600 in^2.
Convert this to square feet by mult. it by (1 ft^2 / 144 in^2):
(600 in^2)(1 ft^2) / (144 in^2) = (600/144) ft^2. Reduce 600/144 to lowest terms.