Creating and manipulating expressions and formulae

  • Odd Differences
    problem

    Odd differences

    Age
    14 to 16
    Challenge level
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    The diagram illustrates the formula: 1 + 3 + 5 + ... + (2n - 1) = n² Use the diagram to show that any odd number is the difference of two squares.

  • Plus Minus
    problem

    Plus minus

    Age
    14 to 16
    Challenge level
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    Can you explain the surprising results Jo found when she calculated the difference between square numbers?

  • Sitting Pretty
    problem

    Sitting pretty

    Age
    14 to 16
    Challenge level
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    A circle of radius r touches two sides of a right angled triangle, sides x and y, and has its centre on the hypotenuse. Can you prove the formula linking x, y and r?

  • Of all the areas
    problem

    Of all the areas

    Age
    14 to 16
    Challenge level
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    Can you find a general rule for finding the areas of equilateral triangles drawn on an isometric grid?

  • Fair Shares?
    problem

    Fair shares?

    Age
    14 to 16
    Challenge level
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    A mother wants to share some money by giving each child in turn a lump sum plus a fraction of the remainder. How can she do this to share the money out equally?

  • What's Possible?
    problem

    What's possible?

    Age
    14 to 16
    Challenge level
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    Many numbers can be expressed as the difference of two perfect squares. What do you notice about the numbers you CANNOT make?

  • Why 24?
    problem

    Why 24?

    Age
    14 to 16
    Challenge level
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    Take any prime number greater than 3 , square it and subtract one. Working on the building blocks will help you to explain what is special about your results.

  • Mediant madness
    problem

    Mediant madness

    Age
    14 to 16
    Challenge level
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    Kyle and his teacher disagree about his test score - who is right?
  • Archimedes and numerical roots
    problem

    Archimedes and numerical roots

    Age
    14 to 16
    Challenge level
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    The problem is how did Archimedes calculate the lengths of the sides of the polygons which needed him to be able to calculate square roots?
  • Number rules - OK
    problem

    Number rules - OK

    Age
    14 to 16
    Challenge level
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    Can you produce convincing arguments that a selection of statements about numbers are true?