Challenge Level

Can you picture how many cubes are in each layer of the six-layered pyramid with 91 cubes in total?

Which layers will have a cube which is directly below cube 1?

Which layers will have a cube which is directly below cube 4? And cube 8?

You might find it useful to record the layers somehow.

Try comparing the positions of the cubes in the first and second pyramids. What do you notice?