Addition and subtraction

  • Mobile Numbers
    problem

    Mobile numbers

    Age
    5 to 11
    Challenge level
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    In this investigation, you are challenged to make mobile phone numbers which are easy to remember. What happens if you make a sequence adding 2 each time?
  • Pros and Cons
    problem

    Pros and cons

    Age
    14 to 16
    Challenge level
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    If p is a positive integer and q is a negative integer, which of these expressions is the greatest?
  • problem

    Caterpillars

    Age
    5 to 7
    Challenge level
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    These caterpillars have 16 parts. What different shapes do they make if each part lies in the small squares of a 4 by 4 square?

  • Pole Star Sudoku 2
    problem

    Pole star Sudoku 2

    Age
    11 to 16
    Challenge level
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    This Sudoku, based on differences. Using the one clue number can you find the solution?

  • Alphabetti Sudoku
    problem

    Alphabetti Sudoku

    Age
    11 to 16
    Challenge level
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    This Sudoku requires you to do some working backwards before working forwards.

  • Two Number Lines
    problem

    Two number lines

    Age
    7 to 11
    Challenge level
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    Max and Mandy put their number lines together to make a graph. How far had each of them moved along and up from 0 to get the counter to the place marked?
  • Number Lines
    problem

    Number lines

    Age
    5 to 7
    Challenge level
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    Leah and Tom each have a number line. Can you work out where their counters will land?

  • Secret Number
    problem

    Secret number

    Age
    5 to 7
    Challenge level
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    Annie and Ben are playing a game with a calculator. What was Annie's secret number?

  • Constellation Sudoku
    problem

    Constellation Sudoku

    Age
    14 to 18
    Challenge level
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    Special clue numbers related to the difference between numbers in two adjacent cells and values of the stars in the "constellation" make this a doubly interesting problem.

  • Making Longer, Making Shorter
    problem

    Making longer, making shorter

    Age
    5 to 7
    Challenge level
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    Ahmed is making rods using different numbers of cubes. Which rod is twice the length of his first rod?