In this problem, each of the nine colours must appear on all six faces of the larger cube.

Small cubes can be placed

- at the corners of the large cube,

- on the edges of the large cube,

- in the middle of the faces of the large cube,

- or at the very centre of the large cube.

A small cube will need to go in at the very centre of the larger cube.

Where will the other two small cubes of the same colour go?