A 5x5x5 cube is formed by assembling 125 unit cubes. Nine unit squares are painted on each of the six faces of the cube according to the pattern shown. How many of the 125 unit cubes have no paint on them?
there are 12 on each side,
how many of those have been double counted? subtract that number
How many have been triple counted. subtract that number twice,
NOW you do it.
No one else answer for the guest, thanks.