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Divisibility rules/Rule for 19 proof

Revision as of 15:42, 20 August 2006 by Mgao (talk | contribs)
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If $k=d_110^0+d_210^1+d_310^2+...$, we can say that $k+2d_0\equiv 20k+2d_0\equiv 10k+d_0$, which is our original number.

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