Monthly Archives: December 2011

The private life of numbers (3): perfect numbers

This is Part 3 of a set of three posts adapted from Mateja Prešern’s talk at The Burn in November 2011. In Part 2 we looked briefly at various sets of numbers, culminating in happy numbers. In this final post, we’ll … Continue reading

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Quotations for the week: Rényi

Two short quotations from Alfréd Rényi, which together give a rather charming picture of the mathematical lifestyle. If I feel unhappy, I do mathematics to become happy. If I am happy, I do mathematics to keep happy. Quoted in P Turán, … Continue reading

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Now pay attention, 007

Some of you may already know that GCHQ has launched an online code-breaking challenge, which can be found at If you like the sound of a career at the mathematical end of government intelligence, it might be worth taking a … Continue reading

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Puzzle: for first years only

Here is a puzzle for 1st years only (i.e. prize only to a 1st year student if solved correctly). Suppose and . What then is ? (There is a very fetching way of solving this by Gröbner bases.) (MG)

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Two more fun fallacies

Here are two more well-known problems that show how easy it is to get confused by formulation or by a persuasive argument. 1. The missing pound. Three men rent a room in a hotel. The owner tells them the price … Continue reading

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