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Infinite series

  1. Apr 27, 2010 #1
    i'm going through a proof and i cant seem to workout why this equality makes sense
    [tex] \sum^{10^{i}-1}_{k=0} \frac{k}{10^i} = \frac{(10^i-1)}{2}[/tex]
    this may be obvious, any hints atleast would be much appreciated
  2. jcsd
  3. Apr 27, 2010 #2
    This is just [tex]\sum\limits_{k=0}^{n-1}k=\frac{n(n-1)}{2}[/tex]; in your problem, replace [tex] n \mbox{ by } 10^i [/tex].

    By the way, your series is a finite one :)
    Last edited: Apr 27, 2010
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