A cube of size 8˝ is coloured red, yellow and orange on the three sets of opposite faces. The cube is then cut into 43 smaller cubes, some of size 4˝ and some of size 2˝. The 4˝ cubes have three of their faces painted red, yellow and orange.
The following questions are based on the smaller cubes of dimensions 2˝ and 4˝.
How many smaller cubes have none of their faces painted?