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Homework Help: Converting to SI units w/ significant digits & scientific notation

  1. May 11, 2012 #1
    I'm asked to convert 2 year into the SI Unit seconds:

    1 Hr = 3600 s
    1 Day = 86400 s

    So using a calculator....
    1 yr = 365*86,400 = 31,536,000

    I want to express the answer in scientific notation:

    Because the lesser number on has 3 significant digits, the scientific notation will also be expressed w/ 3 significant digits. Correct?

    The coefficient in scientific notation must be greater then 1 and less then 10. Correct?

    My answer:
    [itex]3.15 * 10^{7}[/itex]
    Book's answer:
    [itex]3.16 * 10^{7}[/itex]

    Why does the book's answer have it rounded up?
  2. jcsd
  3. May 11, 2012 #2
    They must have used 365.25 days for the length of a year.

  4. May 11, 2012 #3
    Thank you for the reply. At first I thought you were joking & the book made no mention. I had no idea 365.25 is the average number of days in a year.
  5. May 11, 2012 #4


    User Avatar

    Staff: Mentor

    You might say it's a bit of a leap :smile:
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