Starting with the number 180, take away 9 again and again, joining up the dots as you go. Watch out - don't join all the dots!

Can you work out how to balance this equaliser? You can put more than one weight on a hook.

Our 2008 Advent Calendar has a 'Making Maths' activity for every day in the run-up to Christmas.

Move just three of the circles so that the triangle faces in the opposite direction.

Can you make a cycle of pairs that add to make a square number using all the numbers in the box below, once and once only?

This was a problem for our birthday website. Can you use four of these pieces to form a square? How about making a square with all five pieces?

A game for 2 people that everybody knows. You can play with a friend or online. If you play correctly you never lose!

Ahmed has some wooden planks to use for three sides of a rabbit run against the shed. What quadrilaterals would he be able to make with the planks of different lengths?

Can you see why 2 by 2 could be 5? Can you predict what 2 by 10 will be?

Can you put the 25 coloured tiles into the 5 x 5 square so that no column, no row and no diagonal line have tiles of the same colour in them?

Play this well-known game against the computer where each player is equally likely to choose scissors, paper or rock. Why not try the variations too?

Take it in turns to place a domino on the grid. One to be placed horizontally and the other vertically. Can you make it impossible for your opponent to play?

Complete the squares - but be warned some are trickier than they look!

Use the interactivity to find out how many quarter turns the man must rotate through to look like each of the pictures.

Can you complete this jigsaw of the multiplication square?

What happens when you try and fit the triomino pieces into these two grids?

If you have only four weights, where could you place them in order to balance this equaliser?

An interactive activity for one to experiment with a tricky tessellation

What are the coordinates of the coloured dots that mark out the tangram? Try changing the position of the origin. What happens to the coordinates now?

Try to stop your opponent from being able to split the piles of counters into unequal numbers. Can you find a strategy?

NRICH December 2006 advent calendar - a new tangram for each day in the run-up to Christmas.

A game for 2 people that can be played on line or with pens and paper. Combine your knowledege of coordinates with your skills of strategic thinking.

Train game for an adult and child. Who will be the first to make the train?

Choose 13 spots on the grid. Can you work out the scoring system? What is the maximum possible score?

You'll need two dice to play this game against a partner. Will Incey Wincey make it to the top of the drain pipe or the bottom of the drain pipe first?

An interactive game for 1 person. You are given a rectangle with 50 squares on it. Roll the dice to get a percentage between 2 and 100. How many squares is this? Keep going until you get 100. . . .

Hover your mouse over the counters to see which ones will be removed. Click to remover them. The winner is the last one to remove a counter. How you can make sure you win?

Imagine a wheel with different markings painted on it at regular intervals. Can you predict the colour of the 18th mark? The 100th mark?

Incey Wincey Spider game for an adult and child. Will Incey get to the top of the drainpipe?

Three beads are threaded on a circular wire and are coloured either red or blue. Can you find all four different combinations?

If you can post the triangle with either the blue or yellow colour face up, how many ways can it be posted altogether?

Use the interactivity to help get a feel for this problem and to find out all the possible ways the balls could land.

Find out how we can describe the "symmetries" of this triangle and investigate some combinations of rotating and flipping it.

Yasmin and Zach have some bears to share. Which numbers of bears can they share so that there are none left over?

Start by putting one million (1 000 000) into the display of your calculator. Can you reduce this to 7 using just the 7 key and add, subtract, multiply, divide and equals as many times as you like?

Use the information about Sally and her brother to find out how many children there are in the Brown family.

What shaped overlaps can you make with two circles which are the same size? What shapes are 'left over'? What shapes can you make when the circles are different sizes?

Choose four of the numbers from 1 to 9 to put in the squares so that the differences between joined squares are odd.

Place the numbers from 1 to 9 in the squares below so that the difference between joined squares is odd. How many different ways can you do this?