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Thread: Phone # puzzler

  1. #1
    2 Star Lounger
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    Phone # puzzler

    I just got this from a friend. If this has been posted here, please direct me to the post so I can see the solution. If not, why does this work??

    HERE IS A MATH TRICK SO UNBELIEVABLE THAT IT WILL STUMP YOU. PERSONALLY I WOULD LIKE TO KNOW WHO CAME UP WITH THIS AND WHY THAT PERSON IS NOT RUNNING THE COUNTRY.

    1. GRAB A CALCULATOR. (YOU WON'T BE ABLE TO DO THIS ONE IN YOUR HEAD)

    2. KEY IN THE FIRST THREE DIGITS OF YOUR PHONE NUMBER (NOT THE AREA CODE)

    3. MULTIPLY BY 80

    4. ADD 1

    5. MULTIPLY BY 250
    6. ADD THE LAST 4 DIGITS OF YOUR PHONE NUMBER

    7. ADD THE LAST 4 DIGITS OF YOUR PHONE NUMBER AGAIN.

    8. SUBTRACT 250

    9. DIVIDE NUMBER BY 2

    DO YOU RECOGNIZE THE ANSWER?

  2. #2
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    Re: Phone # puzzler

    It is a nice little conundrum which uses a method to introduce factors by stealth. To spoil the illusions it can broken down into a mathematical equation:

    x = first 3 digits
    y = last 4 digits

    1) 80x

    2) 80x+1

    3) 250(80x+1)

    =>250(80x+1)+2y

    4) 250(80x+1)+2y-250

    5) (250(80x+1)+2y-2502/2

    6) Factor 2 out of the numerator:
    =>2[125(80x+1)+y-125]/2

    7) Cancel out 2:
    =>125(80x+1)+y-125

    =>10000x+125+y-125

    =>10000x+y
    Jerry

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    Re: Phone # puzzler

    << DO YOU RECOGNIZE THE ANSWER? Well, I get (kind of) my phone number but not quite. I get the first 3 digits, a stray 1, and the last 3 digits.

    So it not work for me!! Maybe I'm just special!! <img src=/S/grin.gif border=0 alt=grin width=15 height=15>

  4. #4
    Plutonium Lounger Leif's Avatar
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    Re: Phone # puzzler

    I suspect it is meant to be used with 7-digit numbers.

    My number is of the typical UK outside-of-a-big-metropolis format: 01234 567890, where the area code is 01234 and my number is 567890.

    If you do the calculation taking the last 6 digits - 567890 - it doesn't work, but does if you include the 4 - i.e. 4567890

    If our numbers were format in 'continental' style, my number would (probably) be written as: 0123 456 7890

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