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Significant Figures concept

  1. Sep 1, 2005 #1
    I don't really get the concept of significant figures. Anyone can help me out?
    1200 X 23.4
    What is that in significant figures?
  2. jcsd
  3. Sep 2, 2005 #2
    *Significant figures = "sigfigs"
    Remember that products will have as many sigfigs as the least accurate multiplier.
    Here, in your case, 1200 [itex] \Rightarrow [/itex] 2 sigfigs, and 23.4 [itex] \Rightarrow [/itex] 3 sigfigs.

    *Therefore, the product will have two sigfigs, represented as [itex] 28000 = 2.8 \cdot 10^4 [/itex]

    ->Just remember the sigfigs product rule here :wink:
  4. Sep 2, 2005 #3
    I always hated those when I was first learning them. Here are the basic rules.

    -All digits except zeros at the beginning of the number are significant.
    i.e 9.12 (3) 0.912 (3) 0.00000912 (3)

    -Terminal zeros @ right of decimal point are significant.
    i.e 912.0 has four.

    Multiplication and division;

    Final answer has the same amount of significant figures as the number with the least sig fig in original problem.

    i.e 34.987 x 54.2 = 1896.3

    Addition and subtraction;

    Final answer has the same number of sig fig as the number with the least number of decimal places.
    i.e 12.9875 + 1.23 = 14.22

    I think the best way to explain it is, you answer can only be as accurate as the least accurate answer. If that makes sense.

    If you still don't get it, I have another way to explain but it's as long, if not longer than this. I don't really want to type that out yet. Haha.

    Hope this helps.
  5. Sep 2, 2005 #4
    Hmm, I always liked sigfigs, never hated learning them.. :smile:
    Last edited: Sep 2, 2005
  6. Sep 2, 2005 #5


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    first term has two sig figs, the second has three, your final product should have two sig figs.
  7. Sep 2, 2005 #6
    Ok, not really hated. But they are easy to get confused on. So as I was learning them I can't say I liked them. :tongue2:

    But after the first few minutes I liked them. Most of the class was still having problems with them by the end though.
  8. Sep 6, 2005 #7
    The concept is very simple, but it is surprisingly easy to make a mistake when working with sigfigs.
  9. Sep 6, 2005 #8
    *Mostly I just double-check my work to ensure proper use of sigfigs :cool:
    However, the stupid mistakes I do make :shy:, are just silly arithmetic errors (working under duress!), usually (+) sometimes (-). Though when working under pressure/duress...double-checking isn't always convenient :rolleyes:
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