[111,111,111] x [111,111,111] =

Discussion in 'Physics & Math' started by Zardozi, Oct 16, 2007.

  1. Zardozi Isvara.... . 1S Evil_Lau Registered Senior Member

    Messages:
    443
    12345678987654321

    derfeltGesp!
     
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  3. NeonBlack Registered Member

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    28
    This is neat, but really not too surprising.

    Because you used the brackets and X for multiplication, I first thought you meant the vector 111x+111y+111z crossed with itself. You really shouldn't do that.
     
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  5. devire Registered Member

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    79
    11 * 11 = 121

    111 * 111 = 12321

    1111 * 1111 = 1234321

    ....

    you get the picture.

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  7. Nickelodeon Banned Banned

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    10,581
    I thought it was cross product too.
     
  8. temur man of no words Registered Senior Member

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    1,330
    I thought it was tensor product.
     
  9. Learned Hand Registered Senior Member

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    361
    I'm not that much of a math whiz to even know "cross product" vs. product; so I thought it was 12345678987654321.

    Guess sometimes the simplest answer is the right one, eh?
     
  10. Cyperium I'm always me Valued Senior Member

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    2,985
    Hmm...but why?

    22*22 gives 484

    so the reason perhaps why it doesn't work in larger numbers than 1 is because the number that would follow would be >9 and thus starting to mess up the rest of the numbers...

    so 222*222 can't give 48(12)84 =) but instead yields 49284 (the "1" in "12" simply adds to the 8, leaving the 2 behind)
     
    Last edited: Oct 21, 2007
  11. invert_nexus Ze do caixao Valued Senior Member

    Messages:
    9,686
    Because of the way the ones stack up.

    011
    011
    -----
    11
    011
    -----
    121

    Pretty simple really.

    Interesting though.
     
  12. superluminal . Registered Senior Member

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    10,717
    I thought it was a WalMart product.
     
  13. Cyperium I'm always me Valued Senior Member

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    2,985
    Oh kay

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    , as you can see in my above example it does work on larger numbers than one, but it scrambles it a bit

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  14. invert_nexus Ze do caixao Valued Senior Member

    Messages:
    9,686
    Yes.
    In fact, 111,111,111 is the highest number it will work with. Add one more one and it screws up the works because you have to start 'carrying the one'.
     
  15. MetaKron Registered Senior Member

    Messages:
    5,502
    Use a larger base.
     
  16. TruthSeeker Fancy Virtual Reality Monkey Valued Senior Member

    Messages:
    15,162
    Mathematics are filled with tons of symetries like this one.

    Ever heard of the guy who teaches kids how to multiply and divide really large numbers at an amazing speed?
     
  17. Cyperium I'm always me Valued Senior Member

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    2,985
    Yes, how does that work?

    If someone knows, it would be great if you taught us, isn't that what sciforums is all about anyway?
     
  18. TruthSeeker Fancy Virtual Reality Monkey Valued Senior Member

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    15,162
    Sorry to disappoint you, but I don't remember how the guy did it.... :shrug:



    One trick that I do always use when I don't have a calculator is dissecting the numbers, making them all multiples of 10. Like this...

    1430=

    1000
    400
    30

    Then I do the calculation. For instance, a simple one: 1430 / 2

    1000/2 = 500
    400/2 = 200
    30/2 = 15
    sum = 715

    Sometimes I do faster shortcuts too. Like this:

    1400/2 = 700
    30/2=15
    sum=715
     
  19. Reiku Banned Banned

    Messages:
    11,238
    Also, if you are attempting to calculate numbers that are multiples of 111, you can use 37 multiplications, and raise it by a factor of 3 each time so...
    111= 3 x 37
    222= 6 x 37
    333= 9 x 37 ect. ect. ... ... ...

    Well, there's my peice anyway.
     
  20. TruthSeeker Fancy Virtual Reality Monkey Valued Senior Member

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    15,162
    That's exactly the kind of trick I've discovered one time. While I was watching the Butterfly Effect, for some bizarre reason. That movie makes my brain behave in a very strange manner... :bugeye:
     
  21. Cyperium I'm always me Valued Senior Member

    Messages:
    2,985
    That's nice.

    When multiplying something *5 like 2398 * 5, you can take (2398/2) * 10 instead. Using your technique together with mine we get:
    2000/2 = 1000
    300/2 = 150
    90/2 = 45
    8/2 = 4
    2398/2 = 1199
    1199 * 10 = 11990

    So 2398 * 5 = 11990

    Easier example is 5 * 26, it's 130 since 26/2 = 13 and 13 * 10 is 130.


    This also works when multiplying with *15, like 230 * 15, first you take 230 * 10 which is 2300, then you take 2300/2 = 1150, and add them 2300 + 1150 = 3450, so 230 * 15 is 3450
     
    Last edited: Oct 22, 2007
  22. TruthSeeker Fancy Virtual Reality Monkey Valued Senior Member

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    15,162
  23. Reiku Banned Banned

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    11,238
    I remember what was a godsave when i was in primary school. We were always taught that the 9x table had a particular design to it... sure you all know it... we were all taught it at some point...
    9x1=9
    9x2=18
    9x3=27
    9x4=36...
    And each answer would raise the left side by a factor of 1, and the left side would descrease by a factor of 1.
     

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