Addition and subtraction

  • Up, down, flying around
    game
    Favourite

    Up, Down, Flying Around

    Age
    11 to 14
    Challenge level

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

  • Number Daisy
    problem
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    Number Daisy

    Age
    11 to 14
    Challenge level

    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?

  • Cryptarithms
    problem
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    Cryptarithms

    Age
    11 to 14
    Challenge level

    Can you crack these cryptarithms?

  • Add to 200
    problem
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    Add to 200

    Age
    11 to 14
    Challenge level

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

  • Forwards Add Backwards
    problem
    Favourite

    Forwards Add Backwards

    Age
    11 to 14
    Challenge level

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

  • Making a difference
    problem
    Favourite

    Making a Difference

    Age
    11 to 14
    Challenge level

    How many different differences can you make?

  • Amazing Card Trick
    problem
    Favourite

    Amazing Card Trick

    Age
    11 to 14
    Challenge level

    How is it possible to predict the card?

  • Weights
    problem
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    Weights

    Age
    11 to 14
    Challenge level

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

  • Impossibilities
    problem
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    Impossibilities

    Age
    11 to 14
    Challenge level

    Just because a problem is impossible doesn't mean it's difficult...

  • Cunning Card Trick
    problem
    Favourite

    Cunning Card Trick

    Age
    11 to 14
    Challenge level

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

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