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Homework Help: Divisibility test

  1. Jan 31, 2005 #1

    I would like to know how to determine whether a number is divisible by 11 or not... say 209.

    I know the divisibility rules from 2 to 10... but how about 11?
  2. jcsd
  3. Jan 31, 2005 #2
  4. Jan 31, 2005 #3


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    Science Advisor

    Add and subtract the digits alternately. The result is divisible by 11, if and only if the original number is.
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