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If you wrote all the possible four digit numbers made by using each of the digits 2, 4, 5, 7 once, what would they add up to?

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

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

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Use the differences to find the solution to this Sudoku.

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In this game the winner is the first to complete a row of three. Are some squares easier to land on than others?

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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?

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Three children are going to buy some plants for their birthdays. They will plant them within circular paths. How could they do this?

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There are exactly 3 ways to add 4 odd numbers to get 10. Find all the ways of adding 8 odd numbers to get 20. To be sure of getting all the solutions you will need to be systematic. What about. . . .

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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?

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

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

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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.

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

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

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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.

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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. . . .

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In this 100 square, look at the green square which contains the numbers 2, 3, 12 and 13. What is the sum of the numbers that are diagonally opposite each other? What do you notice?

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

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

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Make a set of numbers that use all the digits from 1 to 9, once and once only. Add them up. The result is divisible by 9. Add each of the digits in the new number. What is their sum? Now try some. . . .

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Play this game to learn about adding and subtracting positive and negative numbers

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

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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?

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

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

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

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A cinema has 100 seats. Show how it is possible to sell exactly 100 tickets and take exactly £100 if the prices are £10 for adults, 50p for pensioners and 10p for children.

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By selecting digits for an addition grid, what targets can you make?

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

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Got It game for an adult and child. How can you play so that you know you will always win?

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Try out some calculations. Are you surprised by the results?

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What happens when you add a three digit number to its reverse?

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Investigate the different ways that fifteen schools could have given money in a charity fundraiser.

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Choose two digits and arrange them to make two double-digit numbers. Now add your double-digit numbers. Now add your single digit numbers. Divide your double-digit answer by your single-digit answer. . . .

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Can you arrange the digits 1,2,3,4,5,6,7,8,9 into three 3-digit numbers such that their total is close to 1500?

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You have four jugs of 9, 7, 4 and 2 litres capacity. The 9 litre jug is full of wine, the others are empty. Can you divide the wine into three equal quantities?

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

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

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A combination mechanism for a safe comprises thirty-two tumblers numbered from one to thirty-two in such a way that the numbers in each wheel total 132... Could you open the safe?

Find out about Magic Squares in this article written for students. Why are they magic?!

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This challenge is to make up YOUR OWN alphanumeric. Each letter represents a digit and where the same letter appears more than once it must represent the same digit each time.

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When I type a sequence of letters my calculator gives the product of all the numbers in the corresponding memories. What numbers should I store so that when I type 'ONE' it returns 1, and when I type. . . .

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This Sudoku requires you to do some working backwards before working forwards.

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

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Ann thought of 5 numbers and told Bob all the sums that could be made by adding the numbers in pairs. The list of sums is 6, 7, 8, 8, 9, 9, 10,10, 11, 12. Help Bob to find out which numbers Ann was. . . .

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