<< 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. ;>) >>
One more thing: The problem with the test for 7 is that you don't always get
the desired result the first time!!
Ex: Does 7 divide 54789? 5478 - 2*9 = 5460 so, does 7 divide 5460?
Heck, I don't know!! 546 - 2*0 = 546 so, does 7 divide 546? Shoot, I
still don't know! 54 - 2*6 = 42 ah, yes 7 divides 42!! So 7 divides
54789!
Now!! With the eleven test........ Whta if I wanted to see if 11 divides
384737848473638484737383? I can't fit that into a regular calculator, but
my test will pop it right away.
Karen who's been talking about this stuff with her Elementary teachers this
week
Orange Coast College
http://members.aol.com/coolmath2/coolmath.htm
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