• TIMMAY@lemmy.world
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    2 months ago

    I remember learning this out of curiosity in the past, but math doesnt stick in my brain unless chemistry is used as a disguise. Where can I read about this method again? Will the wiki page on Gauss get me there efficiently enough?

    • noodlejetski@lemm.ee
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      2 months ago

      you’ll either get there, or to the Boston Molasses Disaster, so you’ll learn something cool either way.

      • TIMMAY@lemmy.world
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        2 months ago

        I know about this one! I think it was a Reactions video, which I believe is the American Chemical Society’s yt channel

      • acetanilide@lemmy.world
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        2 months ago

        Just wanted to say thanks! Clicking your link made me realize I should try to figure out how to open up YT on PipePipe automatically, so now my phone works better :)

        • SzethFriendOfNimi@lemmy.world
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          2 months ago

          No problem. I have a script that automates generating the title and link to a video when sharing automatically.

          I should look into having it do the same for pipe

    • mister_monster@monero.town
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      2 months ago

      The sum of all natural numbers smaller than and including x is equal to

      (x+1)(x/2)

      The sum of all even numbers up to and including x is that minus (n/2)² so

      [(x+1)(x/2)]-(x/2)²

      That would mean the sum of all odd numbers under x is equal to

      (x/2)²

      or sum of all odd including x (if x is odd of course) is

      [(x+1)/2]²

      Since the sum of all even numbers up to x is the sum of all numbers minus the sum of all odd numbers.

      [-(x/2)² +2x +1]/2 (another way of writing the sum of all evens under and including a number) looks suspiciously polynomial. I want to go further.

      Edit:

      Interestingly, the sum of all evens under and including x is larger than the sum of all odds under x by half of x. So

      [(x+1)(x/2)-(x/2)²]-(x/2) = (x/2)²

      So another formula for sum of all evens is

      (x/2)²+(x/2)

      So,

      2[(x/2)²]+(x/2) = (x+1)(x/2)

      The left is the sum of all odds plus the sum of all evens under and including x, the right is the original formula we started with, sum of all natural numbers under and including x. Since they both give us the total sum for all natural numbers up to and including x, the left hand side is a different formula giving us the same result!

  • Tarquinn2049@lemmy.world
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    2 months ago

    There is a bit of a typo in it. Since the list of 100 numbers was split in half, it should be x50 not x100. 50 sets of 101 from each pair.

    • Aceticon@lemmy.world
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      2 months ago

      2S = 100 sets of 101

      hence

      S = 100/2 sets of 101 = 50 sets of 101 = 5050

      I wondered about the same thing so did the Maths (which is kinda the point of the meme) back from 5050 and it all checks out.

      • Tarquinn2049@lemmy.world
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        2 months ago

        Oh ok. Yeah fair. I guess I’m used to the simplified version. Where it doesn’t use the full list, just splits it in half. This method would also work for odd lists of numbers rather than only even. Makes sense.