i think the question is incomplete
it should be
if only the surface of a rubric cube of dimension 10 by 10 by 10 is painted then
how many cubes have paint on it (1 cube is 1 * 1 * 1)
answer is 488
total 1000 cubes - (8 * 8 * 8)
1000 - 512 (inner rubric cube) = 488