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Math Help - Very tricky business

  1. #1
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    Very tricky business

    I cant remember how to do it but i know its possible.
    using only the numbers 6, 7, 8, 9, 10.
    using only the operations +, -, /, *
    you have to make 12
    in addition you are only alowed to use them once and you have to use all of them
    parentheses are alowed, but powers are not.
    Last edited by Tzar; October 29th 2010 at 05:54 AM.
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  2. #2
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    Spoiler:
    How about 9 * 8 / 6?
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  3. #3
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    Quote Originally Posted by Ackbeet View Post
    Spoiler:
    How about 9 * 8 / 6?
    Where are 10 and {+,-}?
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  4. #4
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    Hmm. Is the problem statement this:

    1. "Using all of the following symbols exactly once, 6, 7, 8, ,9, 10 and +, -, *, /, try and make the number 12." or is it

    2. "Using any of the following symbols at most once, 6, 7, 8, ,9, 10 and +, -, *, /, try and make the number 12."?

    The OP wasn't worded clearly there, in my opinion.
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  5. #5
    MHF Contributor Also sprach Zarathustra's Avatar
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    Yes...
    My English is bad...
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  6. #6
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    sorry let me reword it.
    using only the numbers 6, 7, 8, 9, 10.
    using only the operations +, -, /, *
    you have to make 12
    in addition you are only alowed to use them once and you have to use all of them
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  7. #7
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    Are parentheses allowed, or do you have to rely on the natural order of operations?
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  8. #8
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    parentheses are alowed, but powers are not.
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  9. #9
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    Quote Originally Posted by Tzar View Post
    using only the numbers 6, 7, 8, 9, 10.
    using only the operations +, -, /, *
    in addition you are only alowed to use them once and you have to use all of them
    Does "them" include the "+, -, /, *" ? Or do you mean just the numbers?

    Like, is 6 * (8 - 7 + 10 - 9) = 12 ok? Or must the / sign be used ?
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  10. #10
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    nope sorry it applies to both the numbers and th operations
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  11. #11
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    Can '/' be interpreted as integer division (where you don't worry about the remainder), or is it real division? Or could it be either?
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  12. #12
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    it has to be real division
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  13. #13
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    Here's one solution. There may be many others.

    Spoiler:
    ((10+8)*7)/6-9.
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  14. #14
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    There are no solutions that can get away without using parentheses.
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  15. #15
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    excellent, thank you, I have been working on it for two weeks
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