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Math Help - (URGENT) How to divide and multiply with decimals.

  1. #1
    Newbie Kitty_Kat's Avatar
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    Exclamation (URGENT) How to divide and multiply with decimals.

    I just need to know the basic rules on how to multiply and divide decimal numbers....Please help! I need this before tommorow so ASAP would be much appreciated.
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  2. #2
    MHF Contributor Quick's Avatar
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    Quote Originally Posted by Kitty_Kat View Post
    I just need to know the basic rules on how to multiply and divide decimal numbers....Please help! I need this before tommorow so ASAP would be much appreciated.
    If you're stuck you can always change 1.01 into (101)/(100)

    There are some tips and tricks if you want to know them...
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  3. #3
    Newbie Kitty_Kat's Avatar
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    Exclamation ...

    So, 1.01 x 2.01 would be 101 x 201? But, if so where would the decimal go in the answer?
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    MHF Contributor Quick's Avatar
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    Quote Originally Posted by Kitty_Kat View Post
    So, 1.01 x 2.01 would be 101 x 201? But, if so where would the decimal go in the answer?
    NO! 1.01 x 2.01 would be:

    Code:
                   101   201   101 x 201   20301
    1.01 x 2.01 =  --- x --- = --------- = ----- = 2.0301
                   100   100   100 x 100   10000
    give me a few minutes and I will post what you need to do without turning them into fractions...
    (but first I have to get chopper challenge back )

    Edit: I was planning to go into detail with some color coding, but I guess topsquark's way of teaching it works (seriously, I was planning on taking like 5 minutes)
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  5. #5
    Forum Admin topsquark's Avatar
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    Quote Originally Posted by Kitty_Kat View Post
    So, 1.01 x 2.01 would be 101 x 201? But, if so where would the decimal go in the answer?
    The usual trick is to count the number of decimals in 1.01 and 2.01 (2 + 2 = 4), calculate 101 x 201 = 20301, then shift the decimal point 4 spaces to the left to get 2.0301.

    Division is a bit trickier: Let's do 1.01 / 23.1. Here we subtract decimals: 2 - 1 = 1. Now calculate 101/231 = 0.43723 or so. Now shift the decimal 1 place to the left: 0.043723. (If the subtraction gives a negative number, as in 10.1/2.31, shift the decimal to the right.)

    -Dan
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  6. #6
    Newbie Kitty_Kat's Avatar
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    Thank you very much.

    ~Cat
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  7. #7
    Forum Admin topsquark's Avatar
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    Quote Originally Posted by Kitty_Kat View Post
    Thank you very much.

    ~Cat
    You are welcome!

    -Dan
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  8. #8
    Member Glaysher's Avatar
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    Another way to do decimal multiplication is this box method
    Attached Thumbnails Attached Thumbnails (URGENT) How to divide and multiply with decimals.-mult.png  
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