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Here is a chance to play a version of the classic Countdown Game.

A game that tests your understanding of remainders.

Can you find a reliable strategy for choosing coordinates that will locate the robber in the minimum number of guesses?

On the graph there are 28 marked points. These points all mark the vertices (corners) of eight hidden squares. Can you find the eight hidden squares?

Can you put the numbers 1-5 in the V shape so that both 'arms' have the same total?

The picture shows a lighthouse and many underwater creatures. If you know the markings on the lighthouse are 1m apart, can you work out the distances between some of the different creatures?

The idea of this game is to add or subtract the two numbers on the dice and cover the result on the grid, trying to get a line of three. Are there some numbers that are good to aim for?

Can you describe the journey to each of the six places on these maps? How would you turn at each junction?

How much do you have to turn these dials by in order to unlock the safes?

Find the product of the numbers on the routes from A to B. Which route has the smallest product? Which the largest?

Can you see how these factor-multiple chains work? Find the chain which contains the smallest possible numbers. How about the largest possible numbers?

Kaia is sure that her father has worn a particular tie twice a week in at least five of the last ten weeks, but her father disagrees. Who do you think is right?

Can you predict when you'll be clapping and when you'll be clicking if you start this rhythm? How about when a friend begins a new rhythm at the same time?

What do the numbers shaded in blue on this hundred square have in common? What do you notice about the pink numbers? How about the shaded numbers in the other squares?

Use the clues about the symmetrical properties of these letters to place them on the grid.

A Sudoku with clues given as sums of entries.

Solve this Sudoku puzzle whose clues are in the form of sums of the numbers which should appear in diagonal opposite cells.

These rectangles have been torn. How many squares did each one have inside it before it was ripped?

Have a look at this table of how children travel to school. How does it compare with children in your class?

Decide which charts and graphs represent the number of goals two football team scored in fifteen matches.

How can you arrange the 5 cubes so that you need the smallest number of Brush Loads of paint to cover them? Try with other numbers of cubes as well.

Use the interactivity to find all the different right-angled triangles you can make by just moving one corner of the starting triangle.

These clocks have only one hand, but can you work out what time they are showing from the information?

An environment which simulates working with Cuisenaire rods.

Which of these sets of numbered balls will give the most even totals when two balls are chosen from them?

This practical problem challenges you to make quadrilaterals with a loop of string. You'll need some friends to help!

Have a go at this game which involves throwing two dice and adding their totals. Where should you place your counters to be more likely to win?

These points all mark the vertices (corners) of ten hidden squares. Can you find the 10 hidden squares?

Players take it in turns to choose a dot on the grid. The winner is the first to have four dots that can be joined to form a square.

Here is a picnic that Chris and Michael are going to share equally. Can you tell us what each of them will have?

Use the lines on this figure to show how the square can be divided into 2 halves, 3 thirds, 6 sixths and 9 ninths.

Find out what a Deca Tree is and then work out how many leaves there will be after the woodcutter has cut off a trunk, a branch, a twig and a leaf.

Systematically explore the range of symmetric designs that can be created by shading parts of the motif below. Use normal square lattice paper to record your results.

Where can you put the mirror across the square so that you can still "see" the whole square? How many different positions are possible?

A magician took a suit of thirteen cards and held them in his hand face down. Every card he revealed had the same value as the one he had just finished spelling. How did this work?
The first of three articles on the History of Trigonometry. This takes us from the Egyptians to early work on trigonometry in China.
In this article Jenny talks about Assessing Pupils' Progress and the use of NRICH problems.

Arrange three 1s, three 2s and three 3s in this square so that every row, column and diagonal adds to the same total.

How would you move the bands on the pegboard to alter these shapes?

Can you find ways of joining cubes together so that 28 faces are visible?