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Thread: 1.09 * 1.09 by hand

  1. #1
    New Member
    Join Date
    Dec 2017
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    4

    1.09 * 1.09 by hand

    Hi everyone,

    I am trying to multiply 1.09 * 1.09 by hand and I am not getting it. Can anyone tell me what I am doing wrong in the calculation?

    1.09
    1.09
    -----
    981
    0000
    98100
    -------
    9.9081

    ?????

    Obviously the answer is 1.1881 but I am doing something wrong with this problem?

  2. #2
    Elite Member
    Join Date
    Jun 2007
    Posts
    17,485
    Quote Originally Posted by pc510 View Post
    hi everyone,

    i am trying to multiply 1.09 * 1.09 by hand and i am not getting it. Can anyone tell me what i am doing wrong in the calculation?

    1.09
    1.09
    -----
    981
    0000
    98100
    -------
    9.9081

    ?????

    Obviously the answer is 1.1881 but i am doing something wrong with this problem?
    xx1.09
    xx1.09
    ----------
    xx981
    x0000
    10900
    -------
    1.1881
    “... mathematics is only the art of saying the same thing in different words” - B. Russell

  3. #3
    Elite Member
    Join Date
    Feb 2004
    Location
    Ottawa, Ontario
    Posts
    17,059
    Well, multiply 109 * 109, then insert the decimal point
    I'm just an imagination of your figment !

  4. #4
    Senior Member
    Join Date
    Nov 2017
    Location
    Rochester, NY
    Posts
    1,021
    Quote Originally Posted by pc510 View Post
    Obviously the answer is 1.1881 but I am doing something wrong with this problem?
    In case the answers you have seen don't make it clear, your error was that you multiplied 1.09 * 9.09 rather than 1.09 * 1.09.

    An important skill in math is to be able to look over your work and find such a "silly" error. This commonly means, first, writing clearly what you did, so that you can compare it with what you intended to do; and, second, reading what you did and comparing with what you intended (in this case, "I intended in the third row to multiply 1.09 by 1 -- but, look! I multiplied by 9 instead"),

  5. #5
    New Member
    Join Date
    Jun 2016
    Posts
    17
    Code:
    1.09   x  1.09
    --000
    ---981
    ======
    1.1881

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