A cuboid-shaped wooden block has 6 cm length, 4 cm breadth and 1 cm height.…

Concept: When a painted cuboid is sliced into unit cubes, a unit cube's colour on any face comes only from the outer surface of the original block that it touches. If the block is exactly 1 unit thick, every unit cube spans the full height, so its top and bottom faces are always part of the block's top and bottom outer faces. The remaining four side faces of a unit cube get colour only when that cube sits on the boundary row or column of the flat grid; an interior cube's four side faces all touch neighbouring cubes, so they stay uncoloured.

Application:

1. The block is 6 cm x 4 cm x 1 cm, cut into unit cubes of side 1 cm, giving 6 x 4 x 1 = 24 cubes arranged as a single 6-by-4 flat grid (one cube thick).

2. Since the height is exactly 1 cm, every one of the 24 cubes automatically has green on both its top and bottom faces (the two 6 cm x 4 cm faces are green) — this holds for every cube, regardless of position.

3. A cube's remaining four side faces are red or black only if that cube lies along the outer edge of the 6-by-4 grid; a cube strictly inside the grid has no side face on the block's boundary.

4. Cubes strictly inside the grid (touching none of the four outer edges) = (6 - 2) x (4 - 2) = 4 x 2 = 8.

5. These 8 cubes therefore have green on exactly two sides (top and bottom) and no colour on the remaining four sides.

Cross-check: The cubes lying along the boundary of the 6-by-4 grid number 24 - 8 = 16, and each of those does carry at least one red or black side face in addition to its two green faces. Interior (8) + boundary (16) = 24, matching the total cube count, which confirms the split.

Result: 8 cubes have green on two sides and no colour on the other four sides.