Working systematically

  • Integer Indices
    problem

    Integer Indices

    Age
    14 to 16
    Challenge level
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    From this sum of powers, can you find the sum of the indices?

  • Leftovers
    problem

    Leftovers

    Age
    14 to 16
    Challenge level
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    Weekly Problem 26 - 2008
    If $n$ is a positive integer, how many different values for the remainder are obtained when $n^2$ is divided by $n+4$?

  • The Great Weights Puzzle
    problem

    The Great Weights Puzzle

    Age
    14 to 16
    Challenge level
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    You have twelve weights, one of which is different from the rest. Using just 3 weighings, can you identify which weight is the odd one out, and whether it is heavier or lighter than the rest?

  • Factor List
    problem

    Factor List

    Age
    14 to 16
    Challenge level
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    Tina has chosen a number and has noticed something about its factors. What number could she have chosen? Are there multiple possibilities?

  • Phone Call
    problem

    Phone Call

    Age
    14 to 16
    Challenge level
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    How many different phone numbers are there starting with a 3 and with at most two different digits?

  • Symmetricality
    problem

    Symmetricality

    Age
    14 to 18
    Challenge level
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    Five equations and five unknowns. Is there an easy way to find the unknown values?

  • Flipping Twisty Matrices
    problem

    Flipping Twisty Matrices

    Age
    14 to 18
    Challenge level
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    Investigate the transformations of the plane given by the 2 by 2 matrices with entries taking all combinations of values 0, -1 and +1.

  • Pole Star Sudoku
    problem

    Pole Star Sudoku

    Age
    14 to 18
    Challenge level
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    A Sudoku based on clues that give the differences between adjacent cells.

  • Twin chute-swapping Sudoku
    problem

    Twin Chute-Swapping Sudoku

    Age
    14 to 18
    Challenge level
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    A pair of Sudokus with lots in common. In fact they are the same problem but rearranged. Can you find how they relate to solve them both?

  • Difference Dynamics
    problem

    Difference Dynamics

    Age
    14 to 18
    Challenge level
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    Take three whole numbers. The differences between them give you three new numbers. Find the differences between the new numbers and keep repeating this. What happens?