Number theory

  • 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.
  • The Codabar Check
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    The Codabar check

    This article explains how credit card numbers are defined and the check digit serves to verify their accuracy.

  • About Pythagorean Golden Means
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    About Pythagorean golden means

    What is the relationship between the arithmetic, geometric and harmonic means of two numbers, the sides of a right angled triangle and the Golden Ratio?

  • Powerful properties
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    Powerful properties

    Yatir from Israel wrote this article on numbers that can be written as $ 2^n-n $ where n is a positive integer.
  • Got \It Article
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    Got it article

    This article gives you a few ideas for understanding the Got It! game and how you might find a winning strategy.
  • Placeholder: several colourful numbers
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    Binomial coefficients

    An introduction to the binomial coefficient, and exploration of some of the formulae it satisfies.