This article for teachers suggests ideas for activities built around 10 and 2010.

Is it possible to rearrange the numbers 1,2......12 around a clock face in such a way that every two numbers in adjacent positions differ by any of 3, 4 or 5 hours?

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

How many solutions can you find to this sum? Each of the different letters stands for a different number.

An account of some magic squares and their properties and and how to construct them for yourself.

Choose four different digits from 1-9 and put one in each box so that the resulting four two-digit numbers add to a total of 100.

We start with one yellow cube and build around it to make a 3x3x3 cube with red cubes. Then we build around that red cube with blue cubes and so on. How many cubes of each colour have we used?

Special clue numbers related to the difference between numbers in two adjacent cells and values of the stars in the "constellation" make this a doubly interesting problem.

This addition sum uses all ten digits 0, 1, 2...9 exactly once. Find the sum and show that the one you give is the only possibility.

Do you notice anything about the solutions when you add and/or subtract consecutive negative numbers?

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

In the following sum the letters A, B, C, D, E and F stand for six distinct digits. Find all the ways of replacing the letters with digits so that the arithmetic is correct.

Different combinations of the weights available allow you to make different totals. Which totals can you make?

Fancy a game of cricket? Here is a mathematical version you can play indoors without breaking any windows.

If you take a three by three square on a 1-10 addition square and multiply the diagonally opposite numbers together, what is the difference between these products. Why?

This challenge extends the Plants investigation so now four or more children are involved.

This challenging activity involves finding different ways to distribute fifteen items among four sets, when the sets must include three, four, five and six items.

First Connect Three game for an adult and child. Use the dice numbers and either addition or subtraction to get three numbers in a straight line.

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

Make your own double-sided magic square. But can you complete both sides once you've made the pieces?

The letters in the following addition sum represent the digits 1 ... 9. If A=3 and D=2, what number is represented by "CAYLEY"?

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.

This Sudoku, based on differences. Using the one clue number can you find the solution?

Crosses can be drawn on number grids of various sizes. What do you notice when you add opposite ends?

This article gives you a few ideas for understanding the Got It! game and how you might find a winning strategy.

Can you find six numbers to go in the Daisy from which you can make all the numbers from 1 to a number bigger than 25?

Five numbers added together in pairs produce: 0, 2, 4, 4, 6, 8, 9, 11, 13, 15 What are the five numbers?

Delight your friends with this cunning trick! Can you explain how it works?

Four bags contain a large number of 1s, 3s, 5s and 7s. Pick any ten numbers from the bags above so that their total is 37.

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?

Find the values of the nine letters in the sum: FOOT + BALL = GAME

Arrange the numbers 1 to 16 into a 4 by 4 array. Choose a number. Cross out the numbers on the same row and column. Repeat this process. Add up you four numbers. Why do they always add up to 34?

Using the 8 dominoes make a square where each of the columns and rows adds up to 8

Use these four dominoes to make a square that has the same number of dots on each side.

For this challenge, you'll need to play Got It! Can you explain the strategy for winning this game with any target?

Use the numbers in the box below to make the base of a top-heavy pyramid whose top number is 200.

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

Use the 'double-3 down' dominoes to make a square so that each side has eight dots.

An investigation involving adding and subtracting sets of consecutive numbers. Lots to find out, lots to explore.

This article suggests some ways of making sense of calculations involving positive and negative numbers.

How can we help students make sense of addition and subtraction of negative numbers?

Find a great variety of ways of asking questions which make 8.

What is the sum of all the digits in all the integers from one to one million?

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

The country Sixtania prints postage stamps with only three values 6 lucres, 10 lucres and 15 lucres (where the currency is in lucres).Which values cannot be made up with combinations of these postage. . . .