On a 3×3×3 cube, all but one 1×1×1 are visible.
How many 1×1×1 cubes are visible on the surface of a 10×10×10 cube?
Everything outside on the surface of the cube is visible.
That means the taking away the outside layer, the inner 8 x 8 x 8 cube would not be visible.
Total number of visible 1 x 1 x 1 cubes = 10×10×10−8×8×8=488
