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

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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?

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Use the differences to find the solution to this Sudoku.

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

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Can you explain the strategy for winning this game with any target?

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

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

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

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

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

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

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

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

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

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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"?

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

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

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

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

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

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

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

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

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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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Skippy and Anna are locked in a room in a large castle. The key to that room, and all the other rooms, is a number. The numbers are locked away in a problem. Can you help them to get out?

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Using some or all of the operations of addition, subtraction, multiplication and division and using the digits 3, 3, 8 and 8 each once and only once make an expression equal to 24.

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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?

This article explains how to make your own magic square to mark a special occasion with the special date of your choice on the top line.

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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?

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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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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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Some Games That May Be Nice or Nasty for an adult and child. Use your knowledge of place value to beat your opponent.

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How many ways can you find to put in operation signs (+ - x Ã·) to make 100?

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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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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.

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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?