1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Oh Mighty Calculator

  1. May 31, 2009 #1
    like many people have done with their calculators, I was dividing 987654321 by 123456789. and I realized...

    sum(0 to N) 987654321 * 10^(N*j)
    divided by
    sum(0 to N) 123456789 * 10^(N*j)

    where N can be any positive integer and j is in the real domain, there is a constant.


    Am I weird and stupid?
     
  2. jcsd
  3. May 31, 2009 #2

    CRGreathouse

    User Avatar
    Science Advisor
    Homework Helper

    sum(0 to N) 987654321 * 10^(N*j) = 987654321 * sum(0 to N) 10^(N*j)
    sum(0 to N) 123456789 * 10^(N*j) = 123456789 * sum(0 to N) 10^(N*j)
    so their quotient is indeed constant.

    I ended up not needing this: For N a positive integer, sum (j=0,N,10^(N*j)) = (10^(N^2+N)-1)/(10^N - 1).
     
  4. Jun 2, 2009 #3
    omg omg I'm like so stup.

    something times (thing/thing) = something.

    how can I be so stupid...
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Oh Mighty Calculator
  1. Oh those identities! (Replies: 2)

  2. Big oh (Replies: 3)

Loading...