<< A number is divisible by 7 IFF it satisfies the following:
Subtract twice the right hand digit from the positive number represented
by the remaining digits. If this difference is divisible by 7, then the
original
number is divisible by 7. Seems to me that it would be easier to use my
calculator and divide by 7 to test for divisibility by 7. ;>) >>
So Barb, what do you think of the divisibility (man, that's hard to type!)
test for 11?
Let's see if I can even describe it well ------
Take the sum of the digits that are in places that are even powers of 10 and
subtract the sum of the digits that are odd powers of 10. If the result is
divisible by 11, then the original number is divisible by 11.
I'd better give an example!
Does 11 divide 28374957?
(7+9+7+8) - (5+4+3+2) = 17 , 11 does not divide 17 so 11 does not divide
that big number we started with! 8-)
Karen
Orange Coast College
http://members.aol.com/coolmath2/coomath.htm
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