DASHCAT4 -- DILR Q.33...why are we considering only the cubes in the surface..in question it has asked for all the cubes that means we should consider all the 343 cubes.

Hi Anwesh, question asks for "If all the single face painted unit cubes". Thus, out of all the cubes, we must consider only the ones that have a single painted face and only the surface cubes are painted. Thus, we have to consider only the surface cubes.