Posers and Puzzles

Posers and Puzzles

  1. Joined
    25 Sep '04
    Moves
    1779
    05 Jan '06 16:36
    http://trunks.secondfoundation.org/files/psychic.swf

    Somebody explain how this works, please.
  2. Standard memberPBE6
    Bananarama
    False berry
    Joined
    14 Feb '04
    Moves
    28719
    05 Jan '06 16:45
    Originally posted by masscat
    http://trunks.secondfoundation.org/files/psychic.swf

    Somebody explain how this works, please.
    The link takes you to a "mind reading crystal ball" and a list of the numbers 0-99 with a concurrent list of symbols. Then it asks you to pick a two-digit number, add the digits together, and subtract that from the original number. After you do this, and you click on the crystal ball, the symbol associated with the result appears.

    I think this has been answered before, but basically this is how it works:

    Let's represent the two digit number as AB. The magnitude of this number is given as 10A + B. The magnitude of the sum of the digits is A + B. If we subtract the sum from the original number, we get:

    10A + B - (A + B) = 9A

    So the result will always be a multiple of 9. Since you can pick any two-digit number from 11-99, A can be any number from 1-9, and the result will be a multiple of 9 from 9 to 81. If you notice on the list, 99 and 90 have the wrong symbol (to throw us of the scent of multiples of 9, I suppose). However, all other multiples of 9 have the correct symbol, so when you click on the crystal ball it seems like the web just read your mind. But it's just some simple math trickery.
  3. Joined
    16 Dec '04
    Moves
    55801
    05 Jan '06 16:46
    The shapes change on the board each time - there's only a certain amount of numbers that you could possibly pick.
  4. Joined
    25 Sep '04
    Moves
    1779
    05 Jan '06 17:05
  5. Joined
    25 Sep '04
    Moves
    1779
    05 Jan '06 17:05
  6. Joined
    25 Sep '04
    Moves
    1779
    05 Jan '06 17:05
  7. Joined
    25 Sep '04
    Moves
    1779
    05 Jan '06 17:05
    Thank ya kindly for the answer. I knew there was a math trick, but didn't know what it was.
  8. Joined
    01 Apr '05
    Moves
    8760
    12 Jan '06 02:55
    as well, there is more than 1 of the same symbol and they are conviently placed on the multipes of nine
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