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Thread: Urgent Help!

  1. Nov 3rd, 2006, 05:20 AM #1
    tomodan
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    Urgent Help!

    Hi, new to the forums and I am trying to resolve a dispute that has arrisen at work. Can anyone point me to the mathmatical proof for the following:

    If you:

    Take any two digit number (eg 38)

    sum the two digits from this number (3+8 = 11)

    Subtract the result from the origional number (38-11 = 27)

    The answer will always be a multiple of 9.

    Can someone show me why this is always the case?

    Much appreciated.
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  2. Nov 3rd, 2006, 05:37 AM #2
    jeroen79
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    Re: Urgent Help!

    The multiple will always be the first digit.

    (10a+b) - (a+b) = 9x
    10a+b - a-b = 9x
    10a - a = 9x
    9a = 9x
    a = x
    VB6 MSDN, AllAPI.
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