Difference between revisions of "Divisibility rules/Rule 2 for 7 proof"
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Revision as of 09:49, 16 August 2006
Proof for Rule 2:
The divisibility rule would be , where , where is the nth digit from the right (NOT the left) and we have and since 2 is relatively prime to 7, . Then yet again , and this is equivalent to our original number.