Edge of cube = 6 cm. Volume of cubes = 6 × 6 × 6 = 216 cm3 Total number of cubes = 216 Each cube has one unit. (a + c) + (b + d) + (e + b) (36 + 36) + (16 + 16) + (24 + 24) = 152 cubes.
Number of unit cubes with no sides painted = 216 − 152 = 64 cubes