• pyre@lemmy.world
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    3 days ago

    i don’t think any number system can be safe from infinite digits. there’s bound to be some number for each one that has to be represented with them. it’s not intuitive, but that’s because infinity isn’t intuitive. that doesn’t mean there’s a problem there though. also the arguments are so simple i don’t understand why anyone would insist that there has to be a difference.

    for me the simplest is:

    1/3 = 0.333…

    so

    3×0.333… = 3×1/3

    0.999… = 3/3

      • pyre@lemmy.world
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        2 days ago

        honestly that seems to be the only argument from the people who say it’s not equal. at least you’re honest about it.

        by the way I’m not a mathematically adept person. I’m interested in math but i only understand the simpler things. which is fine. but i don’t go around arguing with people about advanced mathematics because I personally don’t get it.

        the only reason I’m very confident about this issue is that you can see it’s equal with middle- or high-school level math, and that’s somehow still too much for people who are too confident about there being a magical, infinitely small number between 0.999… and 1.

        • lightnsfw@reddthat.com
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          2 days ago

          to be clear I’m not arguing against you or disagreeing the fraction thing demonstrates what you’re saying. It just really bothers me when I think about it like my brain will not accept it even though it’s right in front of me it’s almost like a physical sensation. I think that’s what cognitive dissonance is. Fortunately in the real world this has literally never come up so I don’t have to engage with it.

          • pyre@lemmy.world
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            2 days ago

            no, i know and understand what you mean. as i said in my original comment; it’s not intuitive. but if everything in life were intuitive there wouldn’t be mind blowing discoveries and revelations… and what kind of sad life is that?

    • Tlaloc_Temporal@lemmy.ca
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      3 days ago

      Any my argument is that 3 ≠ 0.333…

      We’re taught about the decimal system by manipulating whole number representations of fractions, but when that method fails, we get told that we are wrong.

      In chemistry, we’re taught about atoms by manipulating little rings of electrons, and when that system fails to explain bond angles and excitation, we’re told the model is wrong, but still useful.

      This is my issue with the debate. Someone uses decimals as they were taught and everyone piles on saying they’re wrong instead of explaining the limitations of systems and why we still use them.

      For the record, my favorite demonstration is useing different bases.

      In base 10: 1/3 0.333… 0.333… × 3 = 0.999…

      In base 12: 1/3 = 0.4 0.4 × 3 = 1

      The issue only appears if you resort to infinite decimals. If you instead change your base, everything works fine. Of course the only base where every whole fraction fits nicely is unary, and there’s some very good reasons we don’t use tally marks much anymore, and it has nothing to do with math.

      • Leate_Wonceslace@lemmy.dbzer0.com
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        6 hours ago

        Any my argument is that 3 ≠ 0.333…

        After reading this, I have decided that I am no longer going to provide a formal proof for my other point, because odds are that you wouldn’t understand it and I’m now reasonably confident that anyone who would already understands the fact the proof would’ve supported.

      • pyre@lemmy.world
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        3 days ago

        you’re thinking about this backwards: the decimal notation isn’t something that’s natural, it’s just a way to represent numbers that we invented. 0.333… = 1/3 because that’s the way we decided to represent 1/3 in decimals. the problem here isn’t that 1 cannot be divided by 3 at all, it’s that 10 cannot be divided by 3 and give a whole number. and because we use the decimal system, we have to notate it using infinite repeating numbers but that doesn’t change the value of 1/3 or 10/3.

        different bases don’t change the values either. 12 can be divided by 3 and give a whole number, so we don’t need infinite digits. but both 0.333… in decimal and 0.4 in base12 are still 1/3.

        there’s no need to change the base. we know a third of one is a third and three thirds is one. how you notate it doesn’t change this at all.

        • Tlaloc_Temporal@lemmy.ca
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          2 days ago

          I’m not saying that math works differently is different bases, I’m using different bases exactly because the values don’t change. Using different bases restates the equation without using repeating decimals, thus sidestepping the flaw altogether.

          My whole point here is that the decimal system is flawed. It’s still useful, but trying to claim it is perfect leads to a conflict with reality. All models are wrong, but some are useful.

          • pyre@lemmy.world
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            2 days ago

            you said 1/3 ≠ 0.333… which is false. it is exactly equal. there’s no flaw; it’s a restriction in notation that is not unique to the decimal system. there’s no “conflict with reality”, whatever that means. this just sounds like not being able to wrap your head around the concept. but that doesn’t make it a flaw.

            • Tlaloc_Temporal@lemmy.ca
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              2 days ago

              Let me restate: I am of the opinion that repeating decimals are imperfect representations of the values we use them to represent. This imperfection only matters in the case of 0.999… , but I still consider it a flaw.

              I am also of the opinion that focusing on this flaw rather than the incorrectness of the person using it is a better method of teaching.

              I accept that 1/3 is exactly equal to the value typically represented by 0.333… , however I do not agree that 0.333… is a perfect representation of that value. That is what I mean by 1/3 ≠ 0.333… , that repeating decimal is not exactly equal to that value.