Challenge Level

Four friends must cross a bridge. How can they all cross it in just 17 minutes?

Challenge Level

Can you find a strategy that ensures you get to take the last biscuit in this game?

Challenge Level

What happens if we change the rules and make the usual straight number line into a circle?

Challenge Level

Can you find a way of predicting the value of large square numbers with the help of our power modulo calculator?

Challenge Level

Investigate what happens when we add or multiply numbers using modular arithmetic.