Explaining, convincing and proving

  • Why stop at Three by One
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    Why Stop at Three by One

    Beautiful mathematics. Two 18 year old students gave eight different proofs of one result then generalised it from the 3 by 1 case to the n by 1 case and proved the general result.

  • Sums of Squares and Sums of Cubes
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    Sums of Squares and Sums of Cubes

    An account of methods for finding whether or not a number can be written as the sum of two or more squares or as the sum of two or more cubes.

  • Transitivity
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    Transitivity

    Suppose A always beats B and B always beats C, then would you expect A to beat C? Not always! What seems obvious is not always true. Results always need to be proved in mathematics.

  • Continued Fractions II
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    Continued Fractions II

    In this article we show that every whole number can be written as a continued fraction of the form k/(1+k/(1+k/...)).

  • Fractional Calculus III
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    Fractional Calculus III

    Fractional calculus is a generalisation of ordinary calculus where you can differentiate n times when n is not a whole number.

  • Sperner's Lemma
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    Sperner's Lemma

    An article about the strategy for playing The Triangle Game which appears on the NRICH site. It contains a simple lemma about labelling a grid of equilateral triangles within a triangular frame.

  • Euler's Formula and Topology
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    Euler's Formula and Topology

    Here is a proof of Euler's formula in the plane and on a sphere together with projects to explore cases of the formula for a polygon with holes, for the torus and other solids with holes and the relationship between Euler's formula and angle deficiency of polyhedra.

  • A computer program to find magic squares
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    A Computer Program to Find Magic Squares

    This follows up the 'magic Squares for Special Occasions' article which tells you you to create a 4by4 magicsquare with a special date on the top line using no negative numbers and no repeats.