Play around with sets of five numbers and see what you can discover about different types of average...

Which countries have the most naturally athletic populations?

How well can you estimate 10 seconds? Investigate with our timing tool.

Use your skill and judgement to match the sets of random data.

If you have a large supply of 3kg and 8kg weights, how many of each would you need for the average (mean) of the weights to be 6kg?

Start with two numbers and generate a sequence where the next number is the mean of the last two numbers...

There are lots of different methods to find out what the shapes are worth - how many can you find?

Six balls are shaken. You win if at least one red ball ends in a corner. What is the probability of winning?

Can you make a right-angled triangle on this peg-board by joining up three points round the edge?

A tilted square is a square with no horizontal sides. Can you devise a general instruction for the construction of a square when you are given just one of its sides?

Can you find any two-digit numbers that satisfy all of these statements?

How many winning lines can you make in a three-dimensional version of noughts and crosses?

There are nasty versions of this dice game but we'll start with the nice ones...

I'm thinking of a rectangle with an area of 24. What could its perimeter be?

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?

Is there a relationship between the coordinates of the endpoints of a line and the number of grid squares it crosses?

Here is a machine with four coloured lights. Can you make two lights switch on at once? Three lights? All four lights?

If you move the tiles around, can you make squares with different coloured edges?

Can you find rectangles where the value of the area is the same as the value of the perimeter?

Identical squares of side one unit contain some circles shaded blue. In which of the four examples is the shaded area greatest?

Polygons drawn on square dotty paper have dots on their perimeter (p) and often internal (i) ones as well. Find a relationship between p, i and the area of the polygons.

What's the largest volume of box you can make from a square of paper?

An aluminium can contains 330 ml of cola. If the can's diameter is 6 cm what is the can's height?

Semi-regular tessellations combine two or more different regular polygons to fill the plane. Can you find all the semi-regular tessellations?

Who said that adding, subtracting, multiplying and dividing couldn't be fun?

Jo made a cube from some smaller cubes, painted some of the faces of the large cube, and then took it apart again. 45 small cubes had no paint on them at all. How many small cubes did Jo use?

Many numbers can be expressed as the difference of two perfect squares. What do you notice about the numbers you CANNOT make?

Caroline and James pick sets of five numbers. Charlie chooses three of them that add together to make a multiple of three. Can they stop him?

Can you find a relationship between the number of dots on the circle and the number of steps that will ensure that all points are hit?

A country has decided to have just two different coins, 3z and 5z coins. Which totals can be made? Is there a largest total that cannot be made? How do you know?

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

Imagine you were given the chance to win some money... and imagine you had nothing to lose...

Which set of numbers that add to 10 have the largest product?

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

When number pyramids have a sequence on the bottom layer, some interesting patterns emerge...

My two digit number is special because adding the sum of its digits to the product of its digits gives me my original number. What could my number be?

How many pairs of numbers can you find that add up to a multiple of 11? Do you notice anything interesting about your results?

Choose four consecutive whole numbers. Multiply the first and last numbers together. Multiply the middle pair together. What do you notice?

Think of a number and follow my instructions. Tell me your answer, and I'll tell you what you started with! Can you explain how I know?

Think of two whole numbers under 10, and follow the steps. I can work out both your numbers very quickly. How?

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

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

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

In 15 years' time my age will be the square of my age 15 years ago. Can you work out my age, and when I had other special birthdays?

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

Imagine we have four bags containing numbers from a sequence. What numbers can we make now?

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

Seven balls are shaken. You win if the two blue balls end up touching. What is the probability of winning?

Can you work out which spinners were used to generate the frequency charts?

If everyone in your class picked a number from 1 to 225, do you think any two people would pick the same number?