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What is the number of significant digits in a integer with trailing 0's ?

  1. Feb 13, 2012 #1
    It seems that there is a possible ambiguity in the number of significant digits if there are trailing 0's, but no decimal point or overline or underline. Specifically, I am looking at the definition of the second, which the Halliday & Resnick book has listed as

    9 192 631 770

    So is this 9 or 10 digits? Should it be presumed that an integer with trailing 0's, but without the decimal point, overline or underline has those 0's as significant or not?
  2. jcsd
  3. Feb 13, 2012 #2
    Of course they are significant. Try taking them out - the number changes.
  4. Feb 13, 2012 #3

    Doc Al

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    Staff: Mentor

    In this particular case--with the definition of the second--that number is meant as an exact number.

    But in general you'd be correct. A measured quantity written as that number is would have 10 digits, with only the first 9 being significant.
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