problem Skeleton Age 11 to 14 Challenge level Can you reconstruct the long division calculation from the 'skeleton'?
problem Sorted Age 14 to 18 Challenge level How can you quickly sort a suit of cards in order from Ace to King?
problem Probably a code? Age 16 to 18 Challenge level Is the regularity shown in this encoded message noise or structure?
problem Stage 5 cipher challenge Age 16 to 18 Challenge level Can you crack these very difficult challenge ciphers? How might you systematise the cracking of unknown ciphers?