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Math Help - Division problem

  1. #1
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    Division problem

    I've done this before, but keep forgetting the method. Is there some way to get it to stick in my head. Easy ones are obvious, but when it gets more difficult I seam to loose my way.

    eg: what is 60 as a percentage of 340.

    60/340 x100 = 17.647 I believe is the correct way, but I want to do it by pen and paper and see what I'm doing.
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  2. #2
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    I use this proportion as a memory aid:
    \frac{\%}{\text{100}} = \frac{\text{is}}{\text{of}}

    You put the numbers next/close to "%", "is", and/or "of" in this proportion and solve for the unknown.

    Some examples:
    1) What is 35% of 220?
    Plug in 35 for "%", 220 for "of", and a variable for "is":
    \frac{35}{\text{100}} = \frac{x}{220}

    2) 42 is what percent of 840?
    Plug in 42 for "is", 840 for "of", and a variable for "%":
    \frac{x}{\text{100}} = \frac{42}{840}

    3) 36 is 12% of what number?
    Plug in 36 for "is", 12 for "%", and a variable for "of":
    \frac{12}{\text{100}} = \frac{36}{x}

    HTH.


    01
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  3. #3
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    I use this proportion as a memory aid:


    You put the numbers next/close to "%", "is", and/or "of" in this proportion and solve for the unknown.

    This works for most problems, however there are some ways of wording percent problems in which the "part" does not follow the word "is." The whole amount does seem to always follow the word "of" though. It is better to think of the proportion as part/whole instead of is/of.
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  4. #4
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    Think about the wording of the fraction.

    For example: what is 60 as a percentage of 340

    If you think that a fraction means something "out of" something else then you have 60 "out of" 340 which is where the 60/340 comes from.

    When you type this into the calculator, you have a decimal answer. To convert a decimal into a percentage, you always x by 100 because a whole is 100%.


    Quote Originally Posted by Stu300 View Post
    I've done this before, but keep forgetting the method. Is there some way to get it to stick in my head. Easy ones are obvious, but when it gets more difficult I seam to loose my way.

    eg: what is 60 as a percentage of 340.

    60/340 x100 = 17.647 I believe is the correct way, but I want to do it by pen and paper and see what I'm doing.
    Follow Math Help Forum on Facebook and Google+

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