A fake Facebook event disguised as a math problem has been one of its top posts for 6 months

I guess remembering grade school order of operation means you're a guinus now? Bar has gotten pretty low...

And it will go even lower as people start relying mpre on AI...
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.
- This right here is exactly why it's been so popular for so long.
G U I N U S.

I know it's probably a typo, but I'm enjoying it.
- I would like to say it was on purpose but it was not :( I might do math, spelling is not my forte.
- It's jeenyus you moran!
  
  All I can envision with that alternative is Whoopi Goldberg with a very fanciful hat serving drinks in space.

For the programmers: operator precedence.

Not a genius. But if subtraction is last, why isn't it 9-4?

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.
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?
  
  they aren’t teaching math.
  
  Yes we are. Adults forgetting it is another matter altogether.
  
  There’s no such thing as “order of operations” in math
  
  Yes there is! 😂
  
  Do you think I’m wrong?
  
  No, I know you're wrong.
  
  If so, why?
  
  If you don't solve binary operators before unary operators you get wrong answers. 2+3x4=14, not 20. 3x4=3+3+3+3 by definition
  
  Yes we are
  
  Yes and no. You teach how to solve equations, but not the fundamentals (and if you do then kudos to you, as it's not a trivial accomplishment). Fundamentals, most of the time, are taught in universities. It's so much easier that way, but doesn't mean it's right. People call it math, which is fair enough, but it's not really math in a sense that you don't understand the underlying principles.
  
  Yes there is!
  
  Nope.
  
  There's only commutation, association, distribution, and identity. It doesn't matter in which order you apply any of those properties, the result will stay correct.
  
  2×2×(2-1)/2 = 2×(4-2)/2 = 1×(4-2) = 4-2 = 2
  
  As you can see, I didn't follow any particular order and still got the correct result. Because no basic principle was broken.
  
  Or I could also go
  
  2×2×(2-1)/2 = 4×(2-1)/2 = 4×(1-0.5) = 4×0.5 = 2
  
  Same result. Completely different order, yet still correct.
  
  My response to the rest goes back to the aforementioned.
  
  You teach how to solve equations, but not the fundamentals
  
  Nope. We teach the fundamentals. Adults not remembering them doesn't mean they weren't taught. Just pick up a Maths textbook. It's all in there. Always has been.
  
  Fundamentals, most of the time, are taught in universities
  
  No they're not. They only teach order of operations from a remedial point of view. Most of them forget about The Distributive Law. I've seen multiple Professors be told by their students that they were wrong.
  
  it’s not really math in a sense that you don’t understand the underlying principles
  
  The Constructivist learners have no trouble at all understanding it.
  
  Nope.
  
  Yep!
  
  There’s only commutation, association, distribution, and identity.
  
  And many proofs of other rules, which you've decided to omit mentioning.
  
  It doesn’t matter in which order you apply any of those properties, the result will stay correct
  
  But the order you apply the operations does matter, hence the proven rules to be followed.
  
  2×2×(2-2)/2
  
  Notably you picked an example that has no addition, subtraction, or distribution in it. That's called cherry-picking.
  
  Completely different order, yet still correct
  
  Yep, because you cherry-picked a simple example where it doesn't matter. It's never going to matter when you only pick operations which have the same precedence.
  
  My response to the rest goes back to the aforementioned
  
  ...cherry-picking.
  
  We teach the fundamentals
  
  Sure. They are, however, not the focus. At least that's not how I've been taught in school. You're not teaching kids how to prove the quadratic formula, do you? No, you teach them how to use it instead. The goal here is different.
  
  They only teach order of operations.
  
  Again, with the order of operations. It's not a thing. I've given you two examples that don't follow any.
  
  The constructivist learners...
  
  That's kinda random, but sure?
  
  And many proofs of other rules...
  
  They all derive from each other. Even those fundamental properties are. For example, commutation is used to prove identity.
  
  But the order you apply operators does matter
  
  2+2-2 = 4-2 = 2+0 = 0
  
  2 operators, no order followed.
  
  If we take your example
  
  2+3×4 then it's not an order of operation that plays the role here. You have no property that would allow for (2+3)×4 to be equal 2+3×4
  
  Look, 2+3×4 = 1+3×(2+2)+1 = 1+(6+6)+1 = 7+7 = 14
  
  Is that not correct?
  
  Notably you picked...
  
  It literally has subtraction and distribution. I thought you taught math, no?
  
  2-2 is 2 being, hear me out, subtracted from 2
  
  Same with 2×(2-2), I can distribute the value so it becomes 4-4
  
  No addition? Who cares, subtraction literally works the same, but in opposite direction. Same properties apply. Would you feel better if I wrote (2-2) as (1+1-2)? I think not.
  
  Also, can you explain how is that cherry-picking? You only need one equation that is solvable out of order to prove order of operation not existing. One is conclusive enough. If I give you two or more, it doesn't add anything meaningful.
  
  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.
  
  A division is defined as a multiplication
  
  No it isn't. Multiplication is defined as repeated addition. Division isn't repeated subtraction. They just happen to have opposite effects if you treat the quotient as being the result of dividing.
  
  Yes, it is. The division of a by b in the set of real numbers and the set of rational numbers (which are, de facto, the default sets used in most professions) is defined as the multiplication of a by the multiplicative inverse of b. Alternative definitions are also based on a multiplication.
  
  That's why divisions are called an auxilliary operation.
  
  Yes, it is
  
  No it isn't.
  
  The division of a by b in the set of real numbers and the set of rational numbers (which are, de facto, the default sets used in most professions) is defined as the multiplication of a by the multiplicative inverse of b
  
  No it isn't. The Quotient is defined as the number obtained when you divide the Dividend by the Divisor. Here it is straight out of Euler...
  
  Alternative definitions are also based on a multiplication
  
  Emphasis on "alternative", not actual.
  
  No it isn't.
  
  Yes, it is.
  
  No it isn't. The Quotient is defined as the number obtained when you divide the Dividend by the Divisor. Here it is straight out of Euler...
  
  I'm defining the division operation, not the quotient. Yes, the quotient is obtained by dividing... Now define dividing.
  
  Emphasis on "alternative", not actual.
  
  The actual is the one I gave. I did not give the alternative definitions. That's why I said they are also defined based on a multiplication, implying the non-alternative one (understand, the actual one) was the one I gave.
  
  Feel free to send your entire Euler document rather than screenshotting the one part you thought makes you right.
  
  Note, by the way, that Euler isn't the only mathematician who contributed to the modern definitions in algebra and arithmetics.
  
  I’m defining the division operation, not the quotient
  
  Yep, the quotient is the result of Division. It's right there in the definition in Euler. Dividend / Divisor = Quotient <= no reference to multiplication anywhere
  
  Yes, the quotient is obtained by dividing… Now define dividing.
  
  You not able to read the direct quote from Euler defining Division? Doesn't mention Multiplication at all.
  
  The actual is the one I gave
  
  No, you gave an alternative (and also you gave no citation for it anyway - just something you made up by the look of it). The actual definition is in Euler.
  
  That’s why I said they are also defined based on a multiplication
  
  Again, emphasis on "alternative", not actual.
  
  implying the non-alternative one (understand, the actual one) was the one I gave
  
  The one you gave bears no resemblance at all to what is in Euler, nor was given with a citation.
  
  Feel free to send your entire Euler document rather than screenshotting the one part
  
  The name of the PDF is in the top-left. Not too observant I see
  
  you thought makes you right
  
  That's the one and only actual definition of Division. Not sure what you think is in the rest of the book, but he doesn't spend the whole time talking about Division, but feel free to go ahead and download the whole thing and read it from cover to cover to be sure! 😂
  
  Note, by the way, that Euler isn’t the only mathematician who contributed to the modern definitions in algebra and arithmetics.
  
  And none of the definitions you have given have come from a Mathematician. Saying "most professions", and the lack of a citation, was a dead giveaway! 😂
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

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

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?
- 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.
  
  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 + --- 2
  
  or
  
  6 + 4 ------- 2
  
  If you wrote 6 + 4 / 2 in a paper you'd get reviewers complaining that it's ambiguous, if you want it to be on one line write (6+4) / 2 or 6 + (4/2) or 6 + ⁴⁄₂ or even ½(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.
  
  And that’s why people don’t write equations like that
  
  Says someone who clearly hasn't looked in any Maths textbooks
  
  If you wrote 6 + 4 / 2 in a paper you’d get reviewers complaining that it’s ambiguous
  
  Only if their Maths was very poor. #MathsIsNeverAmbiguous
  
  Working mathematicians never came up with PEMDAS
  
  Yes they did.
  
  which disambiguates it without parenthesis
  
  It was never ambiguous to begin with.
  
  Noone else does it that way
  
  Says someone who has never looked in a non-U.S. Maths textbooks - BIDMAS, BODMAS, BEDMAS, all textbooks have one variation or another.
  
  6 + 4 / 2 is 8 instead of 5?
  
  The fundamental property of Maths that you have to solve binary operators before unary operators or you end up with wrong answers.
  
  But +, -, *, and / are all binary operators.
  
  As far as I know, the only reason multiplication and division come first is that we've all agreed to it. But it can't be derived in a vacuum as that other dude contends it should be.
  
  But +, -, *, and / are all binary operators?
  
  No, only multiply and divide are. 2+3 is really +2+3, but we don't write the first plus usually (on the other hand we do always write the minus if it starts with one).
  
  As far as I know, the only reason multiplication and division come first is that we’ve all agreed to it.
  
  No, they come first because you get wrong answers if you don't do them first. e.g. 2+3x4=14, not 20. All the rules of Maths exist to make sure you get correct answers. Multiplication is defined as repeated addition - 3x4=3+3+3+3 - hence wrong answers if you do the addition first (just changed the multiplicand, and hence the answer). Ditto for exponents, which are defined as repeated multiplication, a^2=(axa). Order of operations is the process of reducing everything down to adds and subtracts on a number line. 3^2=3x3=3+3+3
  
  Typical examples of binary operations are the addition ( + {\displaystyle +}) and multiplication ( × {\displaystyle \times }) of numbers and matrices
  
  Very confidently getting basic facts wrong doesn't inspire confidence in the rest of your comments.
  
  Your example still doesn't give a reason why 2 + 3 * 4 is 2 + 3 + 3 + 3 +3 instead of 2 + 3 + 2 + 3 + 2 + 3 + 2 + 3 other than that we all agree to it.
  
  Maths is not about memorisation
  
  It is for ROTE learners.
  
  You are not supposed to remember that the area of a triangle is a * h / 2
  
  Yes you are. A lot of students get the wrong answer when they forget the half.
  
  you’re supposed to understand why it’s the case
  
  Constructivist learners can do so, ROTE learners it doesn't matter. As long as they all know how to do Maths it doesn't matter if they understand it or not.
  
  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
  
  No they're not.
  
  If you’ve understood that once, there is no reason to remember anything because you can derive the formula at a moment’s notice.
  
  And if you haven't understood it then there is a reason to remember it.
  
  you can derive the formula at a moment’s notice
  
  Students aren't expected to be able to do that.
  
  All maths can be understood and derived like that
  
  It can be by Constructivist learners, not ROTE learners.
  
  The names of the colours, their ordering, the names of the planets and how they’re ordered, they’re arbitrary
  
  No they're not. Colours are in spectrum order, the planets are in order from the sun.
  
  Maths doesn’t, instead it dies when you apply memorisation
  
  A very substantial chunk of the population does just fine with having memorised Maths.
  
  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.
  
  You might be smart
  
  Smart-arse more like. A serial troll who doesn't actually know what they're talking about.
  
  just say you like the smell of your own farts, it would be less text for us to read for the same result
- I'm a BEDMAS man myself
- What’s lazy about learning PEMDAS?
  
  Nothing. Only people who don't know what they're talking about say that.