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…
Lost In Stupid Parenthesis.
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.
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
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.
And it will go even lower as people start relying mpre on AI…
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.
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.
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.
Boomers and Xgens need to prove, that they remember basic school math in FB lmao.
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.
Hung up lol
See what you want to see ignorant one. Funny af.
So order of operations is hard?
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) 😄
Another common issue is thinking “parentheses go first” and then beginning by solving the operation beside them (mostly multiplication). The point being that what’s inside the parentheses goes first, not what’s beside them.
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=5Oh 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.Oh, but of course the statement changes if you add parentheses. Basically, you’re changing the effective numbers that are being used, because the parentheses act as containers with a given value (you even showed the effective numbers in your examples).
Get this : + 1 - 1 + 1 - 1 + 1 - 1 + 1
You can change the result several times by choosing where you want to put the parentheses. However, the order of operations of same priority inside a container (parentheses) does not change the resulting value of the container.
In the example, there were no parentheses, so no ambiguity (there wouldn’t be any ambiguity with parentheses either, the correct way of calculating would just change), and I don’t think you can add “ambiguity” by adding parentheses — you’re just changing the effective expression to be evaluated.
By the way, this is the reason why I absolutely overuse parentheses in my engineering code. It can be redundant, but at least I am SURE that it is going to follow the order that I wanted.
So 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.
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.
Ah, yes. It’s only for genius.
Arguing about maths is like dancing to architecture.
question: is there something more than the expression evaluating to 11?
Every one of these only makes me say “wouldn’t it be great if we did everything with RPN”?
So if it’s not really an event
And it’s not really a math problem
What the hell is it??
