Every one of these only makes me say “wouldn’t it be great if we did everything with RPN”?
Arguing about maths is like dancing to architecture.
Hey, some architecture is asking for it like Stonehenge
Anyone on Facebook that attempts to answer this or engage within its comments has already failed the test.
Anyone on Facebook
that attempts to answer this or engage within its commentshas already failed the test.
question: is there something more than the expression evaluating to 11?
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How do you get 5?
Multiplication and division go first, so it’s 9-1+3=11
Yes I deleted my answer haha brain fart… I did 9-(1+3)
So order of operations is hard?
Next they’re going to have an epic debate on whether work done by the system is positive or negative and are all going to feel really smart and passionate about it. Like one of those Science vs Religion debate clubs from the 2000s
Yeah and I’m tired of pretending it’s not!
The issue normally with these “trick” questions is the ambiguous nature of that division sign (not so much a problem here) or people not knowing to just go left to right when all operators are of the same priority. A common mistake is to think division is prioritised above multiplication, when it actually has the same priority. Someone should have included some parenthesis in PEDMAS aka. PE(DM)(AS) 😄
The same priority operations can be done in any order without affecting the result, that’s why they can be same priority and don’t need an explicit order.
6 × 4 ÷ 2 × 3 ÷ 9 evaluates the same regardless of order. Can you provide a counter example?
Another person already replied using your equation, but I felt the need to reply with a simpler one as well that shows it:
9-1+3=?
Subtraction first:
8+3=11Addition first:
9-4=5So let’s try out some different prioritization systems.
Left to right:
(((6 * 4) / 2) * 3) / 9 ((24 / 2) * 3) / 9 (12 * 3) / 9 36 / 9 = 4Right to left:
6 * (4 / (2 * (3 / 9))) 6 * (4 / (2 * 0.333...)) 6 * (4 / 0.666...) 6 * 6 = 36Multiplication first:
(6 * 4) / (2 * 3) / 9 24 / 6 / 9Here the path divides again, we can do the left division or right division first.
Left first: (24 / 6) / 9 4 / 9 = 0.444... Right side first: 24 / (6 / 9) 24 / 0.666... = 36And finally division first:
6 * (4 / 2) * (3 / 9) 6 * 2 * 0.333... 12 * 0.333.. = 4It’s ambiguous which one of these is correct. Hence the best method we have for “correct” is left to right.
I stand corrected
Maybe I’m wrong but the way I explain it is until the ambiguity is removed by adding in extra information to make it more specific then all those answers are correct.
“I saw her duck”
Until the author gives me clarity then that sentence has multiple meanings. With math, it doesn’t click for people that the equation is incomplete. In an English sentence, ambiguity makes more sense and the common sense approach would be to clarify what the meaning is
100% with you. “Left to right” as far as I can tell only exists to make otherwise “unsolvable” problems a kind of official solution. I personally feel like it is a bodge, and I would rather the correct solution for such a problem to be undefined.
It’s so we don’t have to spam brackets everywhere
9+2-1+6-4+7-3+5=
Becomes
((((((9+2)-1)+6)-4)+7)-3)+5=
That’s just clutter for no good reason when we can just say if it doesn’t have parentheses it’s left to right. Having a default evaluation order makes sense and means we only need parentheses when we want to deviate from the norm.
It’s ambiguous which one of these is correct. Hence the best method we have for “correct” is left to right.
The solution accepted anywhere but in the US school system range from “Bloody use parenthesis, then” over “Why is there more than one division in this formula why didn’t you re-arrange everything to be less confusing” to “50 Hertz, in base units, are 50s-1”.
More practically speaking: Ultimately, you’ll want to do algebra with these things. If you rely on “left to right” type of precedence rules re-arranging formulas becomes way harder because now you have to contend with that kind of implicit constraint. It makes everything harder for no reason whatsoever so no actual mathematician, or other people using maths in earnest, use that kind of notation.
I fully agree that if it comes down to “left to right” the problem really needs to be rewritten to be more clear. But I’ve just shown why that “rule” is a common part of these meme problems because it is so weird and quite esoteric.
Oh my god now this is going to be Lemmy’s top thread for 6 months, isn’t it?
Btw, yeah I’m with you on this, you just need to know the priorities and you’re good, because the order doesn’t matter for operations with the same priority
Except it does matter. I left some examples for another post with multiplication and division, I’ll give you some addition and subtraction to see order matter with those operations as well.
Let’s take:
1 + 2 - 3 + 4Addition first:
(1 + 2) - (3 + 4)
3 - 7 = -4Subtraction first:
1 + (2 - 3) + 4
1 + (-1) + 4 = 4Right to left:
1 + (2 - (3 + 4))
1 + (2 - 7)
1 + (-5) = -4Left to right:
((1 + 2) - 3) + 4
(3 - 3) + 4 = 4Edit: You can argue that, for example, the addition first could be
(1 + 2) + (-3 + 4)in which case it does end up as 4, but in my opinion that’s another ambiguous case.
This kind of problem falls under “communicating badly and acting smug when misunderstood”. Use parenthesis and the problem goes away.
on that note, can we please have parentheses in language. i keep making ambiguous sentences
My language teachers always told me it was bad form to use too much or even to nest parenthesis…
Then I found lisp…
This is why grammar is important, and “grammar nazis” are the only good kind of nazis.
People try and use commas for this sort of clarification and are eviscerate for it.
With these sort of math problems, the rules are taught early and then all subsequent math is written in an unambiguous form.
Language has the oddity of going the other way around where the rules get more complex as a display for advanced skills.
eviscerated
God, can you even spell???
Get your act together./s
We have them in written language, though?
Isn’t that basically what commas are for?
Why (I don’t see) not
I was good at math and it was one of my favorite core subjects in school, so I know I’m a weirdo but… I never understood how people couldn’t understand basic PEMDAS/BEDMAS/Whatever-the-fuck-your-country-calls-it.
Obviously these problems are shitty engagement bait because they don’t use parentheses, but still, seeing people fuck up the fact that Multiplication AND Division occur at the same time, and then the next step is Addition AND Subtraction just stupefies me.
Like, did you sleep through 4 years of elementary school to miss that fact??? Even in middle school pre-algebra teachers still did PEMDAS refreshers. I get that once I get out of college I’m probably gonna forget half the pre-calc shit I learned because I won’t need it, and I’m not being drilled on it everyday like people in school are, but PEMDAS is a fundamental and basic daily life skill that everyone should know…
I really wish we gave a fuck about US education.
I never understood how people couldn’t understand basic PEMDAS/BEDMAS/Whatever-the-fuck-your-country-calls-it.
There’s no “whatever-the-fuck-your-country-calls-it”, the US is the only country using it, and only up to high school. At least I’m not seeing any papers coming out of the US relying on it so at some point they’re dropping it and do what everyone else is doing: Write equations such that you don’t need a left-to-right rule to disambiguate things. Also, using multiplication by juxtaposition (2x + 4x2).
I was bad at math, but I still managed to get through precal and still remember PEMDAS
For me it’s the arguments when there is a parentheses but no operator (otherwise known as implied multiplication) in these baits e.g. 15 + 2(4 - 2)
If you don’t know operator orders I have given up long ago, but I have seen a few lengthy discussions about this
Oh yeah, that’s a fun one.
Where I live, this would be considered juxtaposition, at least by uni professors and scientific community, so 2(4-2) isn’t the same as 2×(4-2), even though on their own they’re equal.
This way, equations such as 15/2(4-2) end up with a definite solution.
So,
15/2(4-2) = 3.75
While
15/2×(4-2) = 15
Usually, however, it is obvious even without assuming juxtaposition because you can look at previous operations. Not to mention that it’s most common with variables (Eg. “2x/3y”).
I’m sure we’re all geniuses here, but just in case…
Please excuse my dear aunt Sally.
Parenthesis, exponents, multiplication, division, addition, subtraction.
Why? Because a bunch of dead Greeks say so!
3x3-3÷3+3
(3x3)-(3÷3)+3
9-1+3
8+3
11
The “why” goes a little further than that.
In actuality, it’s because of fundamental properties of operations
- Commutation
a + b = b + a
a×b = b×a
- Association
(a + b) + c = a + (b + c)
(a×b)×c = a×(b×c)
- Identity
a + 0 = a
a×1 = a
If you know that, then PEMDAS and such are useless because they’re derived from those properties but do not fully encompass them.
Eg.
3×2×(2+2) = 3×(4+4) = 12+12 = 24
This is a correct solution that is improper if you’re strictly adhering to PEMDAS rule as I’ve done multiplication before parenthesis from right to left.
I could even go completely out of order by doing 3×2×(2+2) = 2×(6+6) and it will still be correct
I guess remembering grade school order of operation means you’re a guinus now? Bar has gotten pretty low…
That’s the point.
Set the bar low, but just high enough that tons of people still trip over it.
Sit back and enjoy the comment wars.
The people who are confident but wrong are too proud to admit they were wrong even if they realize it, and comment angrily.
The people who are right and know why, comment for corrections and some to show off how S-M-R-T they are.
The people who are wrong but willing to accept that just have their realization and probably don’t think about it again. So do the people who don’t know and/or care.
But those first two groups will keep the post going in both shares and comments, because “look at all these wrong people”
It’s all designed to boost engagement.
I like the version where these problems are made purposefully ambiguous so people will fight over it and raise the level of interaction
This right here is exactly why it’s been so popular for so long.
And it will go even lower as people start relying mpre on AI…
G U I N U S.
I know it’s probably a typo, but I’m enjoying it.
It’s jeenyus you moran!
All I can envision with that alternative is Whoopi Goldberg with a very fanciful hat serving drinks in space.
I would like to say it was on purpose but it was not :( I might do math, spelling is not my forte.
For the programmers: operator precedence.
Not a genius. But if subtraction is last, why isn’t it 9-4?
Parenthesis, exponents, multiplication, division, addition, subtraction.
should actually be
Parenthesis, exponents, (multiplication and division), (addition and subtraction).
Addition and subtraction are given the same priority, and are done in the same step, from left to right.
It’s not a great system of notation, it could be made far clearer (and parenthesis allow you to make it as clear as you like), but it’s essentially the universal standard now and it’s what we’re stuck with.
No, it should simply be “Parenthesis, exponents, multiplication, addition.”
A division is defined as a multiplication, and a substraction is defined as an addition.
I am so confused everytime I see people arguing about this, as this is basic real number arithmetics that every kid in my country learns at 12 yo, when moving on from the simplified version you learn in elementary school.
You want PEMA with knowledge of what is defined, when people can’t even understand PEMDAS. You wish for too much.
I hate most math eduction because it’s all about memorizing formulas and rules, and then memorizing exceptions. The user above’s system is easier to learn, because there’s no exceptions or weirdness. You just learn the rule that division is multiplication and subtraction is addition. They’re just written in a different notation. It’s simpler, not more difficult. It just requires being educated on it. Yes, it’s harder if you weren’t obviously, as is everything you weren’t educated on.
That’s because (strictly speaking) they aren’t teaching math. They’re teaching “tricks” to solve equations easier, which can lead to more confusion.
Like the PEMDAS thing that’s being discussed here. There’s no such thing as “order of operations” in math, but it’s easier to teach by assuming that there is.
Edit: To the people downvoting: I want to hear your opinions. Do you think I’m wrong? If so, why?
I’m just confused as to how that is not common knowledge. The country I speak of is France, and we’re not exactly known for our excellent maths education.
Because its not really “1 plus 3”, its negative 1 plus 3 which is two. I know it seems a little weird but the minus sign is " tied" to the thing following it.
Addition/subtraction work out the same regardless of how you order the operations. If you do subtraction last you start with the original:
9-1+3
and you are adding 3 to the result of (9-1). Since you are trying to perform it before the (9-1) operation is carried out, you can add 3 to the 9:
12-1 = 11
or you can add three to the -1 and get:
9+2 = 11
You only end up with 9-4 if you were subtracting 3 rather than adding three. It all becomes more obvious if you read the original as:
9 + (-1) + 3
It’s multiplication or division from left to right followed by addition or subtraction, also from left to right.
That’s where a lot of people fuck up.
Why? Because a bunch of dead Greeks say so!
The Greeks certainly didn’t come up with PEMDAS. US teachers too lazy to teach kids actual maths did. And that’s before taking into account that the Greeks didn’t come up with Algebra.
US teachers too lazy to teach kids actual maths did.
What’s lazy about learning PEMDAS? And what’s the non-lazy/superior way?
I’m a BEDMAS man myself
Learning the actual algebraic laws, instead of an order of operations to mechanically replicate. PEMDAS might get you through a standardised test but does not convey any understanding, it’s like knowing that you need to press a button to call the elevator but not understand what elevators are for.
Though “lazy teachers” might actually be a bit too charitable a take given the literacy rates of US college graduates mastering in English. US maths teachers very well might not understand basic maths themselves, thinking it’s all about a set of mechanical operations.
You might be smart, but you’re still wrong about the importance of order of operations; especially in algebra.
As far as teachers go, you’re being a dick by generalizing all (US) teachers are lazy and do not understand math.
Pro tip: opinions are like assholes; you too have one, and yes it too stinks.
This guy is the the guy posting the answer and then spending hours fighting the idiots who got it wrong on Facebook.
Nerd.
x/0 is the set {+inf,-inf}, fite me IRL.
Is it also lazy to learn Roy G. Biv to know the color spectrum instead of learning all the physics and optical properties behind that?
Or what about My Very Elderly Mother Just Served Us Nine Pickles to know the planets instead of learning orbital dynamics and astrophysics?
Christ man, it’s a mnemonic device for elementary schoolers.
Those two things are memorisation tasks. Maths is not about memorisation.
You are not supposed to remember that the area of a triangle is
a * h / 2, you’re supposed to understand why it’s the case. You’re supposed to be able to show that any triangle that can possibly exist is half the area of the rectangle it’s stuck in: Start with the trivial case (right-angled triangle), then move on to more complicated cases. If you’ve understood that once, there is no reason to remember anything because you can derive the formula at a moment’s notice.All maths can be understood and derived like that. The names of the colours, their ordering, the names of the planets and how they’re ordered, they’re arbitrary, they have no rhyme or reason, they need to be memorised if you want to recall them. Maths doesn’t, instead it dies when you apply memorisation.
Ein Anfänger (der) Gitarre Hat Elan. There, that’s the Guitar strings in German. Why do I know that? Because my music theory knowledge sucks. I can’t apply it, music is all vibes to me but I still need a way to match the strings to what the tuner is displaying. You should never learn music theory from me, just as you shouldn’t learn maths from a teacher who can’t prove
a * h / 2, or thinks it’s unimportant whether you can prove it.What fundamental property of the universe says that
6 + 4 / 2 is 8 instead of 5?
Nothing. And that’s why people don’t write equations like that: You either see
4 6 + --- 2or
6 + 4 ------- 2If you wrote
6 + 4 / 2in a paper you’d get reviewers complaining that it’s ambiguous, if you want it to be on one line write(6+4) / 2or6 + (4/2)or6 + ⁴⁄₂or even½(6 + 4)Working mathematicians never came up with PEMDAS, which disambiguates it without parenthesis, US teachers did. Noone else does it that way because it does not, in the slightest, aid readability.
just say you like the smell of your own farts, it would be less text for us to read for the same result
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Multiplication and Division, and Addition and Subtraction are executed at the same level and done in left to right order.
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Because it’s just a mnemonic to remember what the order of operations is, not like… What the order of operations is, which you should know already if you know the mnemonic.
Because it’s the only other thing about that system at all. OP wasn’t teaching, just showing what that system does. If you looked for a source that explains it you’d be told
This is the kind of post designed to invoke a reaction. Facebook’s and pretty much every other algorithm driven social media is designed to promote posts that have high interaction. So a post that invokes lots of negative reactions gets lots of promotion. Hence the downfall of modern society.
Boomers and Xgens need to prove, that they remember basic school math in FB lmao.
Please don’t include X with the boomers. Since we stepped into the real world and realized it functions completely differently than what we were raised to believe, life’s just been a neverending string of “wait, that was wrong too?” We just want to survive another day under the radar.
Sorry fellow X’rs for publicly acknowledging our existence. Hopefully this post doesn’t get any upvotes. *Pulls blanket back over my head.
The first rule of gen-x is you don’t talk about gen-x!
As a millennial, I’m starting to relate more and more. The world changes very quickly, and all of the sudden things you knew as fact have different meanings, and there are new words and stuff. It’s not all bad change, but it’s change, and odds are, I’m finding out something changed the hard way.
Seriously, I was raised with so much propaganda.
Up until my late twenties I had believed basically everything I was taught in school. I never had reason to question it, as I was basically living in a bubble. Imagine my surprise when I discovered that when the colonists arrived to this country, it wasn’t just big empty open spaces that the native Americans gladly shared with us. Funny enough, that’s roughly when I gained access to the internet.
The average home buyer in the US 17 years ago was born in 1968. Today? 1968. Yeah excuse me but as an elder millennial, Gen X can mostly fuck right off.
You understand that gen x starts around 1965, right? Your stat says they’re mostly getting fucked too.
I’m on the cusp of X and millennial, so I’ve been around plenty of both.
Some X’s have done well for themselves, but those without a bit of luck and assistance have mostly had to give up on big dreams of housing security and family.
Millennials have had it tougher, but many of them still got there, with a bit more luck and assistance.
It’s been a long decline, with the concentration of capital making it harder for most of us every year. The generational divide is just another distraction from class warfare.
And you understand that 68 is after 65? They’re not getting. Fucked, they’re the last ones to be able to afford housing ownership. If the average is 68 that means one side of the bell curve extends well into the generation.
I’m more worried about the gratuitous comma and what it means for the state of education.
What, gratuitous, comma?
The one after the prove.
Nah, people can write things while being a bit drunk, you know. I’m speaking for a friend, not me, ofc.
Gen xers? Don’t irk them. They’re not noticing you right now.
Very independent, and cranky generation.
Who, the people who never had calculators in their pockets growing up? No worries, we can do math better than you.
lmao
Knowing basic arithmetic does not mean you know Math, and the fact you so hung up about this trivial aspect says a lot about you. Additionally, you express yourself like a boomer.
"Hey, this is Presh Talwalkar.
Discussion of a brief history of this viral math problem, followed by explanations of common incorrect answers. Ultimately followed by brief discussion on the order of operations, concluding in a final example that equals 11
And that’s the answer. Thank you so much for making us one of the best communities on YouTube, where we solve the world’s problems, one video at a time."
So if it’s not really an event
And it’s not really a math problem
What the hell is it??
Engagement bait
Entertainment.
The only thing that will remain on yt anyway after AI has taken over the content generation and we can trust no “creator” anymore.
What’s the scam?
Not strictly a scam, but there’s a little money to be made creating viral content on Facebook. They receive a tiny portion of the ad revenue from Facebook when they generate engagement.
It’s just Facebook sucking really.
Thanks 🙏
OK, it’s been a few hours. I’ll do the clumsy thing that everyone else has avoided and point out that it’s deliberately set up so that people who have never heard of operator precedence - those who do things purely left-to-right - don’t get a weird fraction when the division step is done, making them think that the answer they’ve reached must be the right one. You’d still get a handful who’d argue regardless, but that whole number ropes in a whole bunch more.
Couple that with the fact that the value reached this way doesn’t match the value obtained from using operator precedence and you get arguments about what the right answer is. And a comment like the one you’re reading right now that’s too long for the hard-of-thinking to read.
“More engagement, baybee [sunglasses smiley emoji] [cash bag emoji]” etc.
11
Yes, we can count. I suppose the question was “So what? What is scummy in some viral post?”
This thread shows that a whole bunch of people need to start taking online education courses. Getting back your algebra skills, some science perhaps, communication, history, etc.
I don’t know where you can get a proper education for that after grade school, but I see Brilliant.org advertised a lot.
÷ could be a minus sign, see: https://en.wikipedia.org/wiki/Division_sign?wprov=sfla1
Except that it has English text above it…
