^This^
This book is full of lovely stuff like that. Well worth £7.
www.amazon.co.uk/Mathematics-Magic-Mystery-Dover-Books/dp/0486203352/ref=sr_1_12?s=books&ie=UTF8&qid=1380626649&sr=1-12&keywords=maths+magic
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Fray Brentos *mega-belms*, Tue 1 Oct 2013, 12:29,
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