Difference of two squares

  • Hollow Squares
    problem
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    Hollow Squares

    Age
    14 to 16
    Challenge level
    1 out of 3

    Which armies can be arranged in hollow square fighting formations?

  • Odd Differences
    problem
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    Odd Differences

    Age
    14 to 16
    Challenge level
    2 out of 3

    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
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    Plus Minus

    Age
    14 to 16
    Challenge level
    2 out of 3

    Can you explain the surprising results Jo found when she calculated the difference between square numbers?

  • What's Possible?
    problem
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    What's Possible?

    Age
    14 to 16
    Challenge level
    2 out of 3

    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
    Favourite

    Why 24?

    Age
    14 to 16
    Challenge level
    2 out of 3

    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.

  • Difference of Two Squares
    problem
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    Difference of Two Squares

    Age
    14 to 16
    Challenge level
    2 out of 3

    What is special about the difference between squares of numbers adjacent to multiples of three?

  • Two blank square picture frames on a wooden floor.
    problem
    Favourite

    2-Digit Square

    Age
    14 to 16
    Challenge level
    3 out of 3

    A 2-digit number is squared. When this 2-digit number is reversed and squared, the difference between the squares is also a square. What is the 2-digit number?

  • Euler's Squares
    problem

    Euler's Squares

    Age
    14 to 16
    Challenge level
    1 out of 3

    Euler found four whole numbers such that the sum of any two of the numbers is a perfect square...

  • DOTS Division
    problem

    DOTS Division

    Age
    14 to 16
    Challenge level
    3 out of 3

    Take any pair of two digit numbers x=ab and y=cd where, without loss of generality, ab > cd . Form two 4 digit numbers r=abcd and s=cdab and calculate: {r^2 - s^2} /{x^2 - y^2}.

  • Small tomato seedlings in pink pots.
    problem

    Square Product

    Age
    14 to 16
    Challenge level
    3 out of 3

    Weekly Problem 10 - 2011
    Will this product give a perfect square?