### Nine Colours

Can you use small coloured cubes to make a 3 by 3 by 3 cube so that each face of the bigger cube contains one of each colour?

### The Spider and the Fly

A spider is sitting in the middle of one of the smallest walls in a room and a fly is resting beside the window. What is the shortest distance the spider would have to crawl to catch the fly?

### Hamiltonian Cube

Weekly Problem 36 - 2007
Find the length along the shortest path passing through certain points on the cube.

# The Perforated Cube

##### Age 14 to 16 Challenge Level:

Edison from Shatin School included some edited versions of the diagram given in the hints to support his argument:

The most is 41 blocks, as is the picture in hints. Every block you try and add will change of of the faces. So the maximum is,

Then you can take away blocks, checking each face projection so its unchanged.
On the far E, you can take away 4 on the top prong, 4 on the bottom prong, and the 1 back block on the middle prong. The middle of the S cannot be removed as it is needed for the S face. The on the close E you can take 4 from the middle prong, and then the back block on the top and bottom prong.
So we have removed $15$ blocks, and you cannot remove any more. So the minimum total is $41-15=26$

Well done Edison, can anyone think of any other interesting projections to aim for?