this post was submitted on 19 Jul 2023
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[–] [email protected] 63 points 11 months ago* (last edited 11 months ago) (13 children)

Sadly, this is actually true, people actually don't know simple math and operation order.

And they ask me why I hold such low expectations for the future 🤦.

[–] [email protected] 54 points 11 months ago (7 children)

To be fair, it’s completely arbitrary, and all of math would be easier to understand, although slightly more verbose, if the only rule of order of operations is “always use parentheses to denote order, there are no implied parentheses”.

lazy mfs from centuries ago who were mortified by the thought of having to write ( and ) too much (lord what i wouldn’t give to hop in a time machine and show them lisp) should not be dictating our mathematical notation in this century. Explicit grouping is always more obvious to the reader.

[–] [email protected] 21 points 11 months ago (2 children)

Maybe for very simple calculations like this one, but for more complex ones parenthesis actually make them much harder to read and write. If you've ever built a complex functions in Excel you know how difficult it gets because for 90% of the excel operations require parenthesis which means it works exactly like you'd want math to work. Just yesterday I had to do a more complex index match search in excel and excel corrected my parenthesis, because when your function is supposed to end with 5 parenthesis good luck keeping track of how many parenthesis you actually need to write out. Similarly if a week later I would have to change something inside that same function it's going to take a lot more time to deconstruct the formula because of the abundance of parenthesis.

And the addition of parenthesis in math is entirely unnecessary because the nature of most operators already dictates the order of operations. Exponents are just multiplications and multiplication are just additions. 2^3^ is the same as 2 x 2 x 2 is the same 2 + 2 + 2 + 2. If you take the example in the image then 2 + 2x4 transposed into additions is 2 + (2 + 2 + 2 + 2), parenthesis added to indicate what used to be the multiplication. Why people get it wrong is because they don't understand the nature of those operators and so they do (2+2)x4 which is how they get (2+2)+(2+2)+(2+2)+(2+2) = 16. The order is clear, you can't do addition before you do multiplication, because multiplication is a certain form of addition, and you can't do multiplication before you do exponents, because exponents are a certain form of multiplication. The inverse functions maintain the same order of the function they're inverting, meaning you can do subtraction before division and you can't do division before rooting. No need for parenthesis for the natural order of operations. Parenthesis serve a purpose when you need to denote exceptions to the natural order of operations, like (2+2) x 4.

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[–] [email protected] 19 points 11 months ago (5 children)

That's true, but it's not that hard either.

[–] [email protected] 8 points 11 months ago

Even then it’s still a quick mistake to make. If I’m not paying attention I could easily make a mistake like this, because I’m used to reading things left to right.

[–] [email protected] 4 points 11 months ago (1 children)

I would love to watch people who say that diagram a sentence, per 10th grade English class rules.

(For the record, PEMDAS).

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[–] [email protected] 10 points 11 months ago* (last edited 11 months ago) (10 children)

Multiplication is a notation which means add some number by itself a number of times.

5 x 3 = 5 +5 + 5

2 * 4 = 2 + 2 + 2 +2

So when you see some like 2 + 4 * 2 it literally means. 2+4+4

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[–] [email protected] 4 points 11 months ago* (last edited 11 months ago) (2 children)

To be clear, it's the standard order of operations (PEMDAS) that is arbitrary. The expression in the post, assuming PEMDAS, is not arbitrary. There's only one correct answer.

Also, I dunno man. The window from where math is complicated enough to have multiple different operators to where expressions get too complicated to be easily readable with just parentheses to denote order should be passed by like, early to mid highschool, if not junior high. Point being, frankly if you're struggling with PEMDAS, your either still a high schooler, or you probably should be.

Or we can all learn polish notation

[–] LonelyWendigo 5 points 11 months ago (1 children)

It's not arbitrary just because you don't understand the how and why of it. The expression could certainly be written more clearly, but that's an entirely separate matter.

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[–] [email protected] 3 points 11 months ago* (last edited 11 months ago)

always use parentheses to denote order, there are no implied parentheses

I completely agree on this, and yes, this is what I always do, cuz... well, we're human, we make mistakes, parentheses makes things easily visible, thus cutting down on mistakes.

Still, I do know operation order, as a rule I mean. In simple calcs like these, making a mistake is almost impossible. Thus, people that answered 16 probably just don't know the order... that is something you learn in 1st, 2nd grade, it's not quantum mechanics we're talking about here.

lazy mfs from centuries ago who were mortified by the thought of having to write ( and ) too much (lord what i wouldn’t give to hop in a time machine and show them lisp) should not be dictating our mathematical notation in this century.

We only do that cuz we're not sure how the compiler will interpret the operation order, and there's waaaay too many versions and different languages to actually remember how each of them interprets math operation order. So, we do a safe bet, put parentheses on everything. Hell, I do it as well, I just can't be bothered to remember if C interprets it like this, Python like that, Rust like... god knows what. They should, in theory, know math operation order, but let's face it, we all do it cuz we've been faced with bugs that are a direct result of the compiler not intepreting things as it should.

That being said, yes, I do agree that prentheses on everything, even math on paper, is the way to go. Plus, even people that don't know operation order, will learn it a lot qucker if you just show them how easy things become once you start using prentheses.

[–] [email protected] 3 points 11 months ago (2 children)

I will literally commit hate crimes against all of humanity if I had to write brackets around all operations in math. Surely remembering 6 things is easier than writing out brackets 100 times a day

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[–] [email protected] 3 points 11 months ago

Bold of you to assume people would get how parentheses work. Especially when multiplying blocks of additive parentheses (unless you'd expect to always write the expanded form, please tell me you wouldn't)

[–] [email protected] 4 points 11 months ago (4 children)

10 isn't an option, so people are putting 13 as the closest?

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[–] [email protected] 51 points 11 months ago (2 children)

Since the correct mathematical answer isn't one of the options, the people picking the other options are representing a real resistance to the order of mathematical logic that binds us.

The real answer is 14 because I'm 14 and this is deep.

[–] [email protected] 8 points 11 months ago (1 children)

13, because it's just as wrong, but it's the closest to 10. ;)

[–] [email protected] 4 points 11 months ago

For me it's 13 because it's the "wrongest" one. Every single number in the term is even so you'd expect people to at least choose something that is even, too. Not only is 13 odd, it's a friggin prime..

[–] [email protected] 6 points 11 months ago
[–] [email protected] 29 points 11 months ago (2 children)

He looks like he just walked straight out of Idiocracy

[–] [email protected] 40 points 11 months ago (1 children)

I’m not sure if you’re aware or not, but at the moment that photo was taken, he was in the middle of trying to interview then-president Trump.

I don’t remember what specific thing Trump said to elicit that reaction, and I’m not really in the mood to re-watch the interview to remind myself. Suffice it to say, Trump said a lot of just absolute nonsense.

[–] [email protected] 3 points 11 months ago

Yeah I'm aware of the interview, but he also looks like the actor from Idiocracy and the expression he was making when he realized the time skip.

[–] flipthetube 8 points 11 months ago

Without realizing he just walked into it.

[–] [email protected] 23 points 11 months ago* (last edited 11 months ago) (1 children)

Pemdas isn't as arbitrary as people in this thread think it is.

I love maths, and I'm going to butcher any attempt to explain why pemdas isnt totally random. But you can look it up if you wanna know more I guess

Besides no one ever uses that notation - by the time you learn about quadratics, you leave multiplication symbols out of the equation entirely and much of the notation changes shape, with division exclusively being expressed as negative powers or fractions.

At that point you aren't going to make mistakes, since each hyperlevel uses a different style of notation. Pemdas is used to teach 4 year olds, and it's fucking dumb. What happens with a log, or sine function. Don't even get me started on integrals and derivatives.

Pemdas is shit, but not because it's abirtary. In fact it's shit because it's a shithole acyromn

[–] Uphillbothways 12 points 11 months ago* (last edited 11 months ago) (8 children)

Pemdas is mostly just factoring, kinda. That's how you should think of it.

2x4 is really 2+2+2+2.

That first 2+(anything else) can't be acted/operated upon until you've resolved more nested operations down to a comparable level.

That's it. It's not arbitrary. It's not magic. It's just doing similar actions at the same time in a meaningful way. It's just factoring the activities.

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[–] [email protected] 20 points 11 months ago (2 children)

I understand why people get 16. But how do they get 14, 15 and... 13???? Trolling, right?

[–] [email protected] 27 points 11 months ago (2 children)

13 is actually the best solution given that 10 isn't an available option.

[–] [email protected] 9 points 11 months ago

I wouldn't call the "best" solution to a clearly wrong option, the same as I wouldn't call the "best" option jumping off a cliff to an assured death instead burning alive on a fire, but yeah it's the option closes to the real one.

[–] [email protected] 7 points 11 months ago

Ohhh I see. Those 26%ers trying their best to approximate

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[–] [email protected] 12 points 11 months ago

I'm really bad at math (due to my severe dyscalculia), but I learned back in school that you should prioritize multiplication over addition. It means: First, you do 2x4 which gives you 8, then you add 2 to that, resulting in 10.

Therefore: 2x4=8+2=10

[–] [email protected] 9 points 11 months ago (2 children)

BEDMAS says you do multiplication before addition, so it's 10.

[–] [email protected] 5 points 11 months ago (1 children)

The one I learnt at the dawn of time was BODMAS.

bracket of Division Multiplication Addition Subtraction.

I learnt this in the 70's early 80's in South Africa, so not sure if things have changed.

[–] [email protected] 7 points 11 months ago

B/P are the same (brackets/parentheses) and O/E are the same (order/exponent), and the order of M and D doesn't matter since those two have equal priority and are evaluated left-to-right. Hence PEMDAS, BODMAS, BEDMAS, etc. are all the same.

[–] Cabrio 3 points 11 months ago (1 children)

Same in POMDSA, PODMAS, BOMDSA, PEMDAS, BEMDSA, et al.

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[–] [email protected] 8 points 11 months ago

Please Excuse My Dear Aunt Sally, muthafuckahs!!

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