Conjecturing and generalising

  • Maximum Scattering
    problem

    Maximum Scattering

    Age
    16 to 18
    Challenge level
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    Your data is a set of positive numbers. What is the maximum value that the standard deviation can take?

  • Integral Sandwich
    problem

    Integral Sandwich

    Age
    16 to 18
    Challenge level
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    Generalise this inequality involving integrals.

  • Fix me or crush me
    problem

    Fix Me or Crush Me

    Age
    16 to 18
    Challenge level
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    Can you make matrices which will fix one lucky vector and crush another to zero?

  • Irrational arithmagons
    problem

    Irrational Arithmagons

    Age
    16 to 18
    Challenge level
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    Can you work out the irrational numbers that belong in the circles to make the multiplication arithmagon correct?

  • Rational Roots
    problem

    Rational Roots

    Age
    16 to 18
    Challenge level
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    Given that a, b and c are natural numbers show that if sqrt a+sqrt b is rational then it is a natural number. Extend this to 3 variables.

  • Cyclic Triangles
    problem

    Cyclic Triangles

    Age
    16 to 18
    Challenge level
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    Make and prove a conjecture about the cyclic quadrilateral inscribed in a circle of radius r that has the maximum perimeter and the maximum area.

  • Few and far between?
    problem

    Few and Far Between?

    Age
    16 to 18
    Challenge level
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    Can you find some Pythagorean Triples where the two smaller numbers differ by 1?

  • Interpolating polynomials
    problem

    Interpolating Polynomials

    Age
    16 to 18
    Challenge level
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    Given a set of points (x,y) with distinct x values, find a polynomial that goes through all of them, then prove some results about the existence and uniqueness of these polynomials.

  • Sum the Series
    article

    Sum the Series

    This article by Alex Goodwin, age 18 of Madras College, St Andrews describes how to find the sum of 1 + 22 + 333 + 4444 + ... to n terms.
  • Maths Trails
    article

    Maths Trails

    The NRICH team are always looking for new ways to engage teachers and pupils in problem solving. Here we explain the thinking behind maths trails.