A game for two people, or play online. Given a target number, say 23, and a range of numbers to choose from, say 1-4, players take it in turns to add to the running total to hit their target.

Charlie has made a Magic V. Can you use his example to make some more? And how about Magic Ls, Ns and Ws?

Try entering different sets of numbers in the number pyramids. How does the total at the top change?

Imagine we have four bags containing a large number of 1s, 4s, 7s and 10s. What numbers can we make?

It's easy to work out the areas of most squares that we meet, but what if they were tilted?

Many numbers can be expressed as the sum of two or more consecutive integers. For example, 15=7+8 and 10=1+2+3+4. Can you say which numbers can be expressed in this way?

Choose any three by three square of dates on a calendar page...

Can you describe this route to infinity? Where will the arrows take you next?

Here is a machine with four coloured lights. Can you develop a strategy to work out the rules controlling each light?

What can you say about the angles on opposite vertices of any cyclic quadrilateral? Working on the building blocks will give you insights that may help you to explain what is special about them.

Watch these videos to see how Phoebe, Alice and Luke chose to draw 7 squares. How would they draw 100?

Can all unit fractions be written as the sum of two unit fractions?

Can you find a way to identify times tables after they have been shifted up?

In a three-dimensional version of noughts and crosses, how many winning lines can you make?

This interactivity invites you to make conjectures and explore probabilities of outcomes related to two independent events.

Is this a fair game? How many ways are there of creating a fair game by adding odd and even numbers?

Liam's house has a staircase with 12 steps. He can go down the steps one at a time or two at time. In how many different ways can Liam go down the 12 steps?