Reasoning, convincing and proving

  • Matching Triangles
    problem

    Matching triangles

    Age
    5 to 7
    Challenge level
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    Can you sort these triangles into three different families and explain how you did it?

  • Nicely Similar
    problem

    Nicely similar

    Age
    14 to 16
    Challenge level
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    If the hypotenuse (base) length is 100cm and if an extra line splits the base into 36cm and 64cm parts, what were the side lengths for the original right-angled triangle?

  • Route Product
    problem

    Route product

    Age
    7 to 11
    Challenge level
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    Find the product of the numbers on the routes from A to B. Which route has the smallest product? Which the largest?

  • Where is the dot?
    problem

    Where is the dot?

    Age
    14 to 16
    Challenge level
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    A dot starts at the point (1,0) and turns anticlockwise. Can you estimate the height of the dot after it has turned through 45 degrees? Can you calculate its height?

  • Growing Garlic
    problem

    Growing garlic

    Age
    5 to 11
    Challenge level
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    Ben and his mum are planting garlic. Can you find out how many cloves of garlic they might have had?

  • Triangle Numbers
    problem

    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?

  • Rarity
    problem

    Rarity

    Age
    16 to 18
    Challenge level
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    Show that it is rare for a ratio of ratios to be rational.
  • So Many Sums
    problem

    So many sums

    Age
    11 to 14
    Challenge level
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    In this addition each letter stands for a different digit, with S standing for 3. What is the value of YxO?
  • Old Order
    problem

    Old order

    Age
    11 to 14
    Challenge level
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    Who is the youngest in this family?