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Homework Help: Significant Figures/Digits

  1. Sep 8, 2006 #1
    I was reading the Intro to Physics PDF file on this forum about significant figures/digits.

    Basically the example used is this; add these numbers up and round off to the correct significant figures/digits:

    37.26972+25.43+0.837+101.22+3.1=167.85672=167.9(1 decimal place)

    I understand why the answer must be given to 1 decimal place, however, according another web site, http://www.chem.sc.edu/faculty/morgan/resources/sigfigs/sigfigs6.html,
    167.85672 should be rounded down to 167.8 (1 d.p.).

    Does anyone know who if anyone is correct?
     
  2. jcsd
  3. Sep 8, 2006 #2

    Doc Al

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    Staff: Mentor

    You must be misreading that link. It clearly says:
    (3) If the digit to be dropped is 5, and if any digit following it is not zero, the last remaining digit is increased by one. For example,

    12.51 is rounded to 13.​
    In the example you gave (167.85672 rounded to 1 decimal), the digit you are dropping is 5 and fits this rule, so the last remaining digit (8) must be rounded up to 9.
     
  4. Sep 8, 2006 #3
    i see now, don't think i read (3) properly as you said, thanks for lcearing that up :biggrin:
     
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