• affiliate@lemmy.world
    link
    fedilink
    arrow-up
    1
    ·
    1 year ago

    i’ve seen a few people leave more algebraic/technical explanations so i thought i would try to give a more handwavy explanation. there are three things we need:

    1. the sum of two numbers doesn’t depend on how those numbers are written. (for example, 1/2 + 1/2 = 0.5 + 0.5.)
    2. 1/3 = 0.33…
    3. 1/3 + 1/3 + 1/3 = 1.

    combining these three things, we get 0.99… = 0.33… + 0.33… + 0.33… = 1/3 + 1/3 + 1/3 = 1.

    it’s worth mentioning the above argument could be refined into an actual proof, but it would require messing around with a formal construction of the real numbers. so it does actually explain “why” 0.99… = 1.

    • Kalkaline @lemmy.one
      link
      fedilink
      arrow-up
      0
      ·
      1 year ago

      It’s so dumb and it makes perfect sense at the same time. There is an infinitely small difference between the two numbers so it’s the same number.

      • KoboldCoterie@pawb.social
        link
        fedilink
        arrow-up
        1
        ·
        edit-2
        1 year ago

        There is no difference, not even an infinitesimally small one. 1 and 0.999… represent the exact same number.

          • KoboldCoterie@pawb.social
            link
            fedilink
            arrow-up
            1
            ·
            1 year ago

            An infinitesimal is a non-zero number that is closer to zero than any real number. An infinitesimal is what would have to be between 0.999… and 1.

            • Ghoelian@feddit.nl
              link
              fedilink
              arrow-up
              0
              ·
              1 year ago

              Wait what

              I always thought infinitesimal was one of those fake words, like gazillion or something

              • KoboldCoterie@pawb.social
                link
                fedilink
                arrow-up
                1
                ·
                1 year ago

                It sounds like it should be, but it’s actually a real (or, non-real, I suppose, in mathematical terms) thing! :)

        • nachom97@lemmy.world
          link
          fedilink
          arrow-up
          0
          ·
          1 year ago

          They said its the same number though, not basically the same. The idea that as you keep adding 9s to 0.9 you reduce the difference, an infinite amount of 9s yields an infinitely small difference (i.e. no difference) seems sound to me. I think they’re spot on.

          • iAmTheTot@kbin.social
            link
            fedilink
            arrow-up
            1
            ·
            1 year ago

            No, there is no difference. Infitesimal or otherwise. They are the same number, able to be shown mathematically in a number of ways.

        • Dandroid@dandroid.app
          link
          fedilink
          arrow-up
          0
          arrow-down
          1
          ·
          1 year ago

          That’s what it means, though. For the function y=x, the limit as x approaches 1, y = 1. This is exactly what the comment of 0.99999… = 1 means. The difference is infinitely small. Infinitely small is zero. The difference is zero.

  • Scrof@sopuli.xyz
    link
    fedilink
    arrow-up
    0
    arrow-down
    2
    ·
    1 year ago

    If you take into account quantum fluctuations each piece will have a uniquely different mass at any given moment of time.