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How does this website read your mind.

  1. Jul 6, 2009 #1
    Hi ,
    A friend sent me this website, and I was wondering how it worked,


    obviously it cant read my mind, and its some kind of mathematical trick, I can initially see that all the answers i come up with are 18 apart and that gift is always the same, but why.

  2. jcsd
  3. Jul 6, 2009 #2
    Hah,it's a liittle tricky.
    Any 2-digital number can be expressed as 10a+b,so what you do in fact is 10a+b-a-b=9a, always a multiple of 9, and you notice that the gifts labled by 9,18,27...are always the same!
  4. Jul 6, 2009 #3


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    Homework Helper

    haha I liked this :biggrin:

    Seriously, its not even like those "think of any number, at 20, multiply by 50, subtract 100... etc." sort of doo-wackies. It's so simple it asks for just one thing from you and gets it right every time. I was so stumped as how it was done, lol post #2 spoilt the fun :tongue2:
  5. Jul 6, 2009 #4
  6. Jul 7, 2009 #5
    Thanks kof9595995 that explains it perfectly, isnt algebra wonderful.

    I've just never seen it applied like that before.

    fleem, thats an interesting site too, very clever.
  7. Jul 7, 2009 #6
    teheh, all the multiples of 9 are the same gifts
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