How to Multiply on Your Fingers

Knowing the times tables is helpful to be able to do mental arithmetic. But it is also useful to have some other tricks to help with multiplying. In these experiments, thumbs count as fingers. Multiplying by Nine Put hands on the table, with fingers spread out. To multiply three by …

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The Golden Section

The golden ratio (also known as the golden section or golden mean, or as the Greek letter ‘phi’) describes a rectangular shape that people find an attractive shape, particularly in art or architecture. No-one is quite sure why this is a particularly pleasing shape, but it appears to be something …

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