Addition and subtraction

  • Highest and Lowest
    problem
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    Highest and Lowest

    Age
    7 to 11
    Challenge level
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    Put operations signs between the numbers 3, 4, 5 and 6 to make the highest possible number and lowest possible number.

  • Zios and Zepts
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    Zios and Zepts

    Age
    7 to 11
    Challenge level
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    On the planet Vuv there are two sorts of creatures. The Zios have 3 legs and the Zepts have 7 legs. The great planetary explorer Nico counted 52 legs. How many Zios and how many Zepts were there?

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    Abundant Numbers

    Age
    7 to 11
    Challenge level
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    48 is called an abundant number because it is less than the sum of its factors (without itself). Can you find some more abundant numbers?

  • Super Shapes
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    Super Shapes

    Age
    7 to 11
    Challenge level
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    The value of the circle changes in each of the following problems. Can you discover its value in each problem?

  • 1, 2, 3 Magic Square
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    1, 2, 3 Magic Square

    Age
    7 to 11
    Challenge level
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    Arrange three 1s, three 2s and three 3s in this square so that every row, column and diagonal adds to the same total.

  • A Square of Numbers
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    A Square of Numbers

    Age
    7 to 11
    Challenge level
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    Can you put the numbers 1 to 8 into the circles so that the four calculations are correct?

  • The Deca Tree
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    The Deca Tree

    Age
    7 to 11
    Challenge level
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    Find out what a Deca Tree is and then work out how many leaves there will be after the woodcutter has cut off a trunk, a branch, a twig and a leaf.

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    A Mixed-Up Clock

    Age
    7 to 11
    Challenge level
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    There is a clock-face where the numbers have become all mixed up. Can you find out where all the numbers have got to from these ten statements?

  • Carrying Cards
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    Carrying Cards

    Age
    7 to 11
    Challenge level
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    These sixteen children are standing in four lines of four, one behind the other. They are each holding a card with a number on it. Can you work out the missing numbers?

  • Number Differences
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    Number Differences

    Age
    7 to 11
    Challenge level
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    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?