Complete the magic square using the numbers 1 to 25 once each. Each
row, column and diagonal adds up to 65.
I have forgotten the number of the combination of the lock on my
briefcase. I did have a method for remembering it...
We start with one yellow cube and build around it to make a 3x3x3 cube with red cubes. Then we build around that red cube with blue cubes and so on. How many cubes of each colour have we used?