This is a most excellent place for technology news and articles.
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 comments~~ has already failed the test.
question: is there something more than the expression evaluating to 11?
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=11
Addition first:
9-4=5
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 = 4
Right to left:
6 * (4 / (2 * (3 / 9)))
6 * (4 / (2 * 0.333...))
6 * (4 / 0.666...)
6 * 6 = 36
Multiplication first:
(6 * 4) / (2 * 3) / 9
24 / 6 / 9
Here 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... = 36
And finally division first:
6 * (4 / 2) * (3 / 9)
6 * 2 * 0.333...
12 * 0.333.. = 4
It'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 + 4
Addition first:
(1 + 2) - (3 + 4)
3 - 7 = -4
Subtraction first:
1 + (2 - 3) + 4
1 + (-1) + 4 = 4
Right to left:
1 + (2 - (3 + 4))
1 + (2 - 7)
1 + (-5) = -4
Left to right:
((1 + 2) - 3) + 4
(3 - 3) + 4 = 4
Edit:
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.
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 + 4x^2^).
I was bad at math, but I still managed to get through precal and still remember PEMDAS
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
a + b = b + a
a×b = b×a
(a + b) + c = a + (b + c)
(a×b)×c = a×(b×c)
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.
And it will go even lower as people start relying mpre on AI...
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!
"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."