My professor has challenged me to prove -or- disprove something.  We all
know have to tell if a number is evenly divisable by 2, just see if it
is odd or even.   If we want to know if a number is divisable by 3, just
add up the digits making up that number until you get s single digit. If
that single digit is divisable by 3 then the original number is also.
For example, 2,637 IS divisable by 3. 2+6+3+7=18.  Add them up again (we
got have a single digit), 1+8=9.  We can divide 3 into 2,637 evenly.
There is also a rule for 4, 5, 6, 8, and 9 that I know of. The professor
challenged me to find on for 7.  He said I could any resource I wanted,
so if you know where I can find out, please tell me.  Better yet, if you
know the formula for this, would you mind  sharing it with me?  I have
already gone through over 200 books at the library, and feel it is time
to try other resources.  All I have to do is prove the rule does not
exist, or find the rule and present it. Thank you. Robert Carneal,

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