Comments

• vane@lemmy.world ⁨1⁩ ⁨hour⁩ ago

  4*75/100 3.5% of 7535*75/1000

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• someacnt@sh.itjust.works ⁨4⁩ ⁨hours⁩ ago

  Ah, joy of commutative algebra.

  Wait until you get to noncommutative algebra… shudders. No one who mastered that monster of a subject is sane in any measure.

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  • Sunrosa@lemmy.world ⁨4⁩ ⁨hours⁩ ago

    Yay for quaternions and beyond

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• idegenszavak@sh.itjust.works ⁨12⁩ ⁨hours⁩ ago

  My engineering brain says it’s 3.25.

  4% is ~ 5%. 10% of 75 if 7.5. To get the 5% I have to divide it by 2, so 4% of 75 is close to 3.25. I will have to multiply it with some safety coefficient at the end, so the exact value doesn’t matter.

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  • saltesc@lemmy.world ⁨5⁩ ⁨hours⁩ ago

    Mine brain just does 0.75 × 4.

    Thought process was…

    1. Get 1% = 0.75
    2. Double it = 1.5
    3. Double it = 3

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  • SatansMaggotyCumFart@piefed.world ⁨12⁩ ⁨hours⁩ ago

    That’s why you can always double the maximum limits engineers give.

    60 mph roadway?

    I can do 120 on it no problem.

    Eight person elevator? Sixteen.

    0.08 BAC? 0.16 easy peasy.

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    • DancingBear@midwest.social ⁨3⁩ ⁨hours⁩ ago

      Can I also smoke two joints before I smoke two joints, and then smoke two more?

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    • idegenszavak@sh.itjust.works ⁨11⁩ ⁨hours⁩ ago

      Yes, in elevators usually one cable could hold far more than the full weight, than they add 6 more for the safety.

      For rail speed limits this is the exact way they calculate it. For road speed limits they consider break distance, which grows by the square of your speed, so if you go 120 on 60 road, you will need 4 times the distance to stop. I wrote 1.5 as a safety factor, not 4, With a 1.5 safety factor you can go by 75 though, but I would use a 1.1 safety there, as in my country the speed cameras are set up that way, you can go +10% of the official speed limit, they only send a cheque if you went even quicker than that.

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    • jballs@sh.itjust.works ⁨5⁩ ⁨hours⁩ ago

      Did engineers come up with that last one though?

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  • One_Honest_Dude@lemmy.world ⁨12⁩ ⁨hours⁩ ago

    I’m confused by this statement, the answer is 3. Why do all these extra steps for a wrong answer?

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    • idegenszavak@sh.itjust.works ⁨11⁩ ⁨hours⁩ ago

      It’s not wrong, it’s close enough. And the point it works with more numbers and more type of calculation. Let’s calculate 4% of 1243. That’s the same as 1243% of 4, right, much easier to calculate by simply changing the 2 numbers… While my method is the same, by simply rounding everything.

      And in engineering you always multiply/divide your results by a 1.5 or 1.25 safety factor, depending on situation. So you don’t have to calculate exact results, just close enough. E.g. G is always 10m/s2. π is only 3.14, the other digits doesn’t matter.

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  • zakobjoa@lemmy.world ⁨12⁩ ⁨hours⁩ ago

    That’s exactly why we have safety coefficients.

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    • IhaveCrabs111@lemmy.world ⁨10⁩ ⁨hours⁩ ago

      Safety coefficients are for nerds

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• TheImpressiveX@lemmy.today ⁨13⁩ ⁨hours⁩ ago

  Answer

  Image

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  • Carvex@lemmy.world ⁨12⁩ ⁨hours⁩ ago

    One…

    A-two

    A-three. Three licks to the Tootsie Roll center of a Tootsie Pop.

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    • Lemminary@lemmy.world ⁨8⁩ ⁨hours⁩ ago

      You bit that, you cheated! I saw you.

      Image

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  • Cat_Daddy@hexbear.net ⁨13⁩ ⁨hours⁩ ago

    Mr. Owl would be proud

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• ZoDoneRightNow@kbin.earth ⁨13⁩ ⁨hours⁩ ago

  0.04 x 75 == 0.75 x 4 == 75 x 4 x 0.01

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  • berber@feddit.org ⁨13⁩ ⁨hours⁩ ago

    switch the order of the last two terms (the second equality), put the 0.01 in the middle, and it makes a bit more sense when read as calculation steps.

    0.04 * 75 = 4 * 0.01 * 75 = 4 * 0.75
    

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    • ZoDoneRightNow@kbin.earth ⁨1⁩ ⁨hour⁩ ago

      That's fair. I intended them to just be a list of equalities

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• zout@fedia.io ⁨8⁩ ⁨hours⁩ ago

  I'd do 4%=1/25, 75/25=3.

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• BigBenis@lemmy.world ⁨11⁩ ⁨hours⁩ ago

  That’s a neat trick but also 4% of 75 = (1% of 75) * 4 = 0.75 * 4 = 1.5 * 2 = 3

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• gravitas_deficiency@sh.itjust.works ⁨13⁩ ⁨hours⁩ ago

  Is it weird that I just went

  start: 75

  to actual decimal: .75 22: 1.5 -> 3

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  • LifeInMultipleChoice@lemmy.dbzer0.com ⁨13⁩ ⁨hours⁩ ago

    Nah we all do weird shit. I did 4x75, then moved from 300. to 3

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    • Zulu@lemmy.world ⁨12⁩ ⁨hours⁩ ago

      Meanwhile im the idiot thats like “uh 10% of 75 is 7.5, half it for 5% of 75 is 3.75, 1% of 75 is .75, so its probably 3?”

      Lets pray thats one of the options on the multiple choice. Oh the professor wants me to show my math? Well lets hope he’s open to me being an abstract dumbass that is capable of getting the right answer.

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    • Lemminary@lemmy.world ⁨8⁩ ⁨hours⁩ ago

      Yes, but then I have to do 4 x 75 = 50 + 25 + 50 + 25 + 50 + 25 + 50 + 25 = 50 + 50 + 50 + 50 + 25 + 25 + 25 + 25 = 200 + 100 = 300 in that same order because non-maths brain.

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    • idiomaddict@lemmy.world ⁨9⁩ ⁨hours⁩ ago

      I just figured 4% is 1/25 and divided 75/25

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  • muhyb@programming.dev ⁨12⁩ ⁨hours⁩ ago

    That’s how my brain works as well.

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• Korhaka@sopuli.xyz ⁨9⁩ ⁨hours⁩ ago

  Even the first one, 0.75 doubled and then doubled again is hard?

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  • affiliate@lemmy.world ⁨8⁩ ⁨hours⁩ ago

    at this point in my life, as somebody with multiple math degrees, if i ever come across a situation where i need to multiply or divide numbers and one of them is bigger than 12, im going to use a calculator.

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    • Objection@lemmy.ml ⁨3⁩ ⁨hours⁩ ago

      Shitty Math Pro Tip: If you ever have to work with numbers larger than 10, convert it to scientific notation and then round to a single significant figure.

      ? = 0.04 x 75
      ? = (4 x 10^-2) x (7.5 x 10^1)
      ? ~= (4 x 10^-2) x (8 x 10^1)
      ? = 4 x 8 x 10^-1
      ? = 32 x 10^-1
      ? = 3.2
      ? ~= 3
      

      See how easy that is? Here’s another one:

      ? = 12 x 12
      ? = (1.2 x 10^1) x (1.2 x 10^1)
      ? ~= (1 x 10^1) x (1 x 10^1)
      ? = 1 x 10^2
      ? = 100
      

      Bam, lock it in.

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    • darvocet@infosec.pub ⁨8⁩ ⁨hours⁩ ago

      Look at Mr big brain over here who learned his times tables. Sure hope nobody takes his lunch money.

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• Soot@hexbear.net ⁨13⁩ ⁨hours⁩ ago

  (4/100) * 75 = (75/100) * 4

  I actually think the mutability of expressions is an under-taught part of maths until you reach like, constructing high-level proofs. Rearranging numbers into already-understood ones is a very useful skill.

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• betanumerus@lemmy.ca ⁨10⁩ ⁨hours⁩ ago

  4 over 100

  X over 75

  And there’s your butterfly.

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• Eheran@lemmy.world ⁨13⁩ ⁨hours⁩ ago

  Sure with easy numbers multiplication is easy. Try anything else.

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• Agent641@lemmy.world ⁨4⁩ ⁨hours⁩ ago

  Just do (7-5)+(5-4)=3

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  • ngdev@lemmy.zip ⁨4⁩ ⁨hours⁩ ago

    i prefer the easier to remember (7 * 4) - (5^(√4))

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