The box has a volume of 64 cubic inches. As volume is length x width x height, we know that the dimensions of the box multiply to give 64. Thus, we are looking for three numbers that multiply to give us 64. Each unique combination we find will give us a different box and therefore a different surface area. The possibilities are as follows:
2x2x16
4x4x4
2x4x8
Therefore, there are 3 possible surface areas.