A rectangular prism 3cm x 5cm x 9cm is painted mauve and is then cut into 1cm^3 cubes. What is the total unpainted surface area of these cubes?
+36916 3 x 5 x 9 is 135 cubes total surface area 6 x 135 = 810 cm2
original painted area = 2 x 3x5 + 2 x 5 x 9 + 2 x 9 x 3 cm2
you should be able to finish.......
