Start with the whole base
This stack has a complete base: two rows of three cubes. Two more cubes sit on the first two cubes of the back row.
Every upper cube rests on a cube below it. Count horizontal layers, including the base cubes covered by the upper layer. A hidden space alone does not tell you whether a cube is there.
Count one layer at a time
Look down at each layer separately. The bottom layer has six cubes. The upper layer has two.
Add the layers: 6 + 2 = 8. The dashed empty positions in the upper layer contain no cubes. Do not count the visible faces as separate cubes.
Try a smaller stack
This new stack has a complete two-by-two base and one cube on its back-left corner. There are no gaps under the upper cube.
Count the bottom layer, then add the upper layer.
Try it
How many cubes are in this smaller stack?
- 5
- 6
Show the answer
5
There are five cubes: four in the complete base and one above it. The covered base cube still belongs to the bottom layer.
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Practice Cube counting