Trick to Multiply by N-1 in Base N
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In base 10, multiplying digits by 9 produces a nice pattern. This Demonstration extends the trick, showing a simple way to multiply by in base .
Contributed by: Izidor Hafner (December 2012)
Open content licensed under CC BY-NC-SA
 B. A. Kordemsky, The Moscow Puzzles, London: Penguin, 1990, p. 91.