The six faces of a three-inch wooden cube are each painted red. The cube is then cut into one-inch cubes along the lines shown in the diagram. How many of the one-inch cubes have red paint on at least one face?
Only ONE will NOT have a red face ...the one in the dead middle so 26 WILL have a red face
The only cube that has no red paint is the one in the middle of the cube.
Since there are 27 cubes, (3 * 3 * 3), 27 - 1 = 26 cubes that have red paint.