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-   -   1 as a sum of unit fractions (https://www.askmehelpdesk.com/showthread.php?t=63665)

  • Feb 17, 2007, 11:23 AM
    galactus
    1 as a sum of unit fractions
    As you may know, a unit fraction is a fraction with 1 in the numerator.

    Can you write 1 as a sum of seven unit fractions? Or even more than 7?
  • Feb 17, 2007, 11:33 AM
    Capuchin
    Infinity unit fractions?

  • Feb 17, 2007, 11:48 AM
    galactus
    You're so right, Cap, but I just wanted to see something more finite. It's not difficult. I am sure you know how.

    .
  • Feb 17, 2007, 11:50 AM
    Capuchin
    I know, I'm just trying to be a smart arse. I'll leave it to others to have a go :)
  • Feb 17, 2007, 12:34 PM
    galactus
    I think I just spoiled that. Maybe I oughta delete it for now.

    BTW, what you done was clever. Showin' off:)
  • Feb 17, 2007, 07:54 PM
    asterisk_man


    Is there an additional complication that I'm missing?
  • Feb 17, 2007, 07:56 PM
    Capuchin
    Yes, the question confused me too, I would think that for many sets of 6 unit fractions you can come up with, you can pick a 7th that will make the sum 1.

    Edit: on second thoughts probably not, but it isn't very hard :/

    I'm thinking he meant different unit fractions, at least there is a little challenge there.
  • Feb 18, 2007, 07:13 AM
    galactus
    Yes, I meant different unit fractions.

    You can string it out however far you want to by using:



    and keep substituting.
  • Feb 26, 2007, 12:33 PM
    MathMaven53
    1 = 1/2 + 1/2
    = 1/2 + (1/2 - 1/3) + 1/3
    = 1/2 + 1/3 + 1/6
    = 1/2 + 1/3 + 1/7 + (1/6 -1/7)
    = 1/2 + 1/3 +1/7 + 1/42
    = 1/2 + 1/4 + (1/3-1/4) + 1/7 + 1/42
    = 1/2 + 1/4 + 1/7 + 1/12 + 1/42
    = 1/2 + (1/4 - 1/5) + 1/5 +1/7 + 1/12 + 1/42
    = 1/2 + 1/5 + 1/7 + 1/12 + 1/20 + 1/42
    = 1/2 + (1/5 - 1/6) + 1/6 + 1/7 +1/12 + 1/20 + 1/42
    = 1/2 + 1/6 + 1/7 + 1/12 + 1/20 + 1/30 + 1/42
  • Feb 16, 2012, 06:18 PM
    go2lilman
    3/4 sun

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