# 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

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Reference

[1] B. A. Kordemsky, *The Moscow Puzzles*, London: Penguin, 1990, p. 91.

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