• 31337@sh.itjust.works
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    3 months ago

    Fractions are easier to do calculations in your head or on paper than trying to do the same stuff in decimals. E.g. half of 1/2 is 1/4, half of 1/4 is 1/8, half of 1/8 is 1/16, half of 1/16 is 1/32 etc. In decimals this would be 0.5 -> 0.25 -> 0.125 -> 0.0625 -> 0.03125. When building stuff, I find it useful to be able to do that kind of stuff in my head easily.

    • dQw4w9WgXcQ@lemm.ee
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      3 months ago

      The problem occurs when you have a 1/4 pound burger for $1 and a 1/3 pound burger for $1.25. Is it worth it?

      If only using fractions in powers of 2 1/2, I understand that it’s simpler. A carpenter is happy to meassure 3/16s of an inch, since the tools have notches or marks for that. But when you include other fractions, it becomes messy.

      How much more is 1/3 than 1/4? Instead of handling digits, you have to find the lowest common denominator to perform the subtraction. I.e. 1/3 - 1/4 = 4/12 - 3/12 = 1/12.

      And at this point, I believe the relationship to the units are lost. Do you have any direct sense to what 1/12 of a pound is?

      The 1/3 pound burger is (1/3)/(1/4) times the size of the 1/4 pound burger. So the burger is worth it if $1*(1/3)/(1/4) is greater than $1.25. We arrive at $4/3 which we want to compare to $1.25. Now, since we are relating units which use fractions to units where fractions are unusual, we have another problem. (Yes, we can easily see tha 4/3 = 1.333…, but we wanted to use fractions, right?). So to compare the numbers, we can see that 1.25 = 125/100, which we can simplify to 5/4. So in the end we are left with the simple problem of finding which is bigger between 4/3 or 5/4.

      To summarize, I agree that fractions are nice when you have them in a vacuum and don’t have to relate them to numbers of other units.

    • hswolf@lemmy.world
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      3 months ago

      why use decimals when you can use the… you know, actual weight of the thing?

        • hswolf@lemmy.world
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          3 months ago

          I get what you mean, but its adding a useless complexity layer.

          If the thing always is smaller than, for example, a kilogram, just use the next measurement unit, a gram. 100g, 200g, 500g, etc.

          It’s true the other way around, if the thing is always bigger than, for example, a kilogram, use it as is. 1kg, 1.5kg, 4kg, 6.2kg.

          For ease of comparison, always use the most significant unit.