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Math Help - help help please

  1. #1
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    help help please

    when two digit number KY is multiplied by itself, the result is the 3 digit number ZLK i.e(KY) x(KY) = ZLK. The number that K stands for is
    a)1 or 9
    b)2 or 6
    c)3
    d)1
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  2. #2
    MHF Contributor

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    Quote Originally Posted by kl050196 View Post
    when two digit number KY is multiplied by itself, the result is the 3 digit number ZLK i.e(KY) x(KY) = ZLK. The number that K stands for is
    a)1 or 9
    b)2 or 6
    c)3
    d)1
    The statement of the problem implies that "Y" does not matter. What is 19*19. Is it a 3 digit number? What about 99*99, 29*29, etc.?

    Since you are squaring, another way to do this is to look at \sqrt{1000}. What does that tell you?
    Last edited by mr fantastic; March 26th 2009 at 03:42 AM. Reason: Fixed the latex tags
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  3. #3
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    Hello, kl050196!

    We can solve this by Elimination.


    When a 2-digit number KY is squared,
    the result is the 3-digit number ZLK . . . i.e (KY)^2 \:=\: ZLK
    The number that K stands for is:

    . . (a)\;1\text{ or }9 \qquad (b)\;2\text{ or }6 \qquad (c)\;3 \qquad (d)\;1
    The answer cannot be (a) since (9Y)^2 \,\geq \,8100

    The answer cannot be (b) because a square cannot end in 2.

    The answer cannot be (c) because a square cannot end in 3.

    Therefore . . .

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