How can you quickly sort a suit of cards in order from Ace to King?
Can you crack these very difficult challenge ciphers? How might you systematise the cracking of unknown ciphers?
Use cunning to work out a strategy to win this game.
Can you set the logic gates so that this machine can decide how many bulbs have been switched on?
Try to solve this very difficult problem and then study our two suggested solutions. How would you use your knowledge to try to solve variants on the original problem?
Here is a machine with four coloured lights. Can you develop a strategy to work out the rules controlling each light?
Many numbers can be expressed as the difference of two perfect squares. What do you notice about the numbers you CANNOT make?