Triangle numbers

  • Satisfying Four Statements
    problem
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    Satisfying Four Statements

    Age
    7 to 11
    Challenge level
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    Can you find any two-digit numbers that satisfy all of these statements?

  • Light the Lights Again
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    Light the Lights Again

    Age
    7 to 11
    Challenge level
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    Each light in this interactivity turns on according to a rule. What happens when you enter different numbers? Can you work out the rule for each light?

  • Picturing Triangular Numbers
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    Picturing Triangular Numbers

    Age
    11 to 14
    Challenge level
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    What do you notice about the sum of two identical triangular numbers?

  • Summing Consecutive Numbers
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    Summing Consecutive Numbers

    Age
    11 to 14
    Challenge level
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    15 = 7 + 8 and 10 = 1 + 2 + 3 + 4. Can you say which numbers can be expressed as the sum of two or more consecutive integers?

  • Factors and Multiples Puzzle
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    Factors and Multiples Puzzle

    Age
    11 to 14
    Challenge level
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    Using your knowledge of the properties of numbers, can you fill all the squares on the board?

  • Route to infinity
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    Route to Infinity

    Age
    11 to 14
    Challenge level
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    Can you describe this route to infinity? Where will the arrows take you next?

  • Triangle Numbers
    problem
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    Triangle Numbers

    Age
    11 to 14
    Challenge level
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    Take a look at the multiplication square. The first eleven triangle numbers have been identified. Can you see a pattern? Does the pattern continue?

  • Handshakes
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    Handshakes

    Age
    11 to 14
    Challenge level
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    Can you find an efficient method to work out how many handshakes there would be if hundreds of people met?
  • Ten colourful lolly sticks in a line.
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    Take Ten Sticks

    Age
    11 to 16
    Challenge level
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    Take ten sticks in heaps any way you like. Make a new heap using one from each of the heaps. By repeating that process could the arrangement 7 - 1 - 1 - 1 ever turn up, except by starting with it?

  • Mystic Rose
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    Mystic Rose

    Age
    14 to 16
    Challenge level
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    Use the animation to help you work out how many lines are needed to draw mystic roses of different sizes.