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Thread: Significant figures problems.

  1. #1 Significant figures problems. 
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    Hi everything,

    Don't worry I know how the significant figures work. However, I don't know how to use the rule here :

    [(81.35 ml -81.321 ml)/ 81.321 ml ] * 100 = ?

    Thanks.


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  3. #2  
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    solve the algebra, round the digits to 3 sig figs, and then determine it's magnitude in terms of


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  4. #3  
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    Wait..wait... why 3 sig figs? Isn't it supposed to be 1 sig fig since 100 = 1sg?

    And why should I put it in 10^n term?
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  5. #4  
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    ... okay, why would you want only 1 sig fig? What use is only 1? and is scientific notation, what is most commonly used with sig figs.
    Wise men speak because they have something to say; Fools, because they have to say something.
    -Plato

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  6. #5  
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    In this case, the 100 is not a measurement, or anything else with an error (which is what sig figs are used to estimate). You could write it 100.00000 to as many figures as you need since you know the value exactly.
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  7. #6  
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    magimaster is right, and in light of that, you need 5 sig figs, not 3. I was just remembering my old highschool chem requirement
    Wise men speak because they have something to say; Fools, because they have to say something.
    -Plato

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  8. #7 Re: Significant figures problems. 
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    Quote Originally Posted by HopeUTKN
    Hi everything,

    Don't worry I know how the significant figures work. However, I don't know how to use the rule here :

    [(81.35 ml -81.321 ml)/ 81.321 ml ] * 100 = ?

    Thanks.
    . If you are working in engineering you'll have to use engineering notation, which is akin to scientific notation with respect to some restrictions (the power of ten must be a multiple of three).
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  9. #8  
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    Thanks guys!
    This helped me a lot!
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  10. #9  
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    There are two measurements: one with two and one with three significant digits. Isn't the lessor of the two the limiting factor in determining how many significant digits are in the answer? If the one measurement were 81.350 ml then there would be three significant digits. But it's 81.35 ml, so the answer should be limited to two significant digits, right? If not then tell me why I'm many ml's all wet.
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