What is the smallest number of answers you need to reveal in order to work out the missing headers?

Can you recreate squares and rhombuses if you are only given a side or a diagonal?

Can you find the hidden factors which multiply together to produce each quadratic expression?

Can you find the values at the vertices when you know the values on the edges of these multiplication arithmagons?

Can you find the values at the vertices when you know the values on the edges?

Charlie likes to go for walks around a square park, while Alison likes to cut across diagonally. Can you find relationships between the vectors they walk along?

Play the game of Poison, Antidote, Water to start to understand the mathematics of associativity and groups.

We received two very good solutions to this problem - one identified an important relationship, the other proved it.

John Mason describes the thinking behind this month's tasks.

The computer starts with all the lights off, but then clicks 3, 4 or 5 times at random, leaving some lights on. Can you switch them off again?