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Let’s keep it easy. There’s 2 + all the other number who results in 15 = 17.
Someone may mistake by doing 2+5 then the rest of the operation, resulting in 21. But is wrong.
(* (+ 2 5) (- 8 5))Hope some LISP can clear this up
Edit:
( + 2 ( * 5 ( - 8 5 ) ) )Is this a meme? Shouldn’t it be
( + 2 ( * 5 ( - 8 5 ) ) )Damn you are right haha.
Mine evals to 21.
Explain yourself sir
This is called “prefix notation”. The operator comes before the operands and every expression goes in parentheses.
For instance you could write:
(+ 1 2 3 4)Which would evaluate to 10.
This syntax is from a family of programming languages usually called LISP.
Awesome thanks for explaining that. That’s cool as hell.
I understand prefix notation, but you got the order of operations wrong…
Yeah I’m stupid
Knowing is half the battle!
Pemdas, parenthesis first, for a total of 3. Then multiplication, 15, then addition. 17. What’s hard about this?
you go the other direction below the equator
Legit gave me pause for like half a second. Damnit lol
I fucking suck at math and totally just re-proved it to myself with this problem lmao.
It didn’t make sense to me to multiply the 3 & the 5 with zero consideration for the “2”. I have ALWAYS struggled with the steps to solve these types of equations.
So the answer I got was 21. Some of us are just bad with numbers, I s’pose.
The numbers in the equation and their totals are completely irrelevant to the order you perform the operations.
I don’t think it’s an issue of “being bad with numbers”, I think the issue is not understanding the logic or being able to understand the bottom up type of thinking or something.
Some other parent’s thesis.
I’m sorry but isn’t this elementary school math?
In the rest of the world: yes.
In the US: I highly doubt it.
This is just basic math, if you can’t figure this out you’re probably 8 years old.
I think that ordering of calculation was taught around 5th grade back in my day (11yo)
We didn’t learn elements until high school tbf
In most of the world? Yes.
My dumbahh did 2+5 like it was in parentheses and got 21
Its because its:
2+5×(8−5)
My calculator app automatically added it when typing in what was in the image and “2+5×(8−5)” does equal 17.
It’s absolutely the fault of the person making the social media media post for not writing it properly and confusing people.
The multiplication is implied and has been part of the standard mathematical notation for far longer than any of us have been alive.
5(8-5) is perfectly fine, it’s like saying 5 apples
What du you mean, not writing it properly?
2 5 8 5 - × + for you RPN fans =)
Actually:
2 <enter> 5 <enter> 8 <enter> 5 - x +
10 keystrokes
I use RPN on my phone calculator for fun but it can also be annoying sometimes.
On my CASIO FX-260 Solar II calculator (super cheap, really nice and simple but also powerful) that would be:
2 + 5 ( 8 - 5 ) =
9 keystrokes
You could do
8 <enter> 5 - 5 × 2 +-> 8 keystrokes
8 5 - 5 * 2 + CR .
But that’s a specific optimization where you can no longer read the numbers left to right, the original intent of RPN.
Im terrible at math, what is this though?
RPN or Reverse Polish Notation is a notation for calculators to be less ambiguous. The last numbers use the operator to their right, repeat. So no need for parenthesis or PEMDAS.
- 2 5 8 5 - × +
- (8 - 5 = 3)
- 2 5 3 × +
- (5 × 3 = 15)
- 15 2 +
- (15 + 2 = 17)
- 17
This might actually help me thank you!
This might actually help me thank you!
I got some people really angry at me when I suggested writing some math expression with parenthesis so it would be clearer. I think someone told me that order of operations is like a natural law and not a convention, and thus everyone should know it or be able to figure it out.
Using parenthesis can really help if you want to simplify a term or need to rewrite something. I do that all the time because a lot of times you then can just cross stuff out fast on equations or get a common term that just has some factor instead of having a convolutet equation.
I got really angry because the prettier code formatter insists on removing parentheses, making things less clear. Because it’s an “opinionated” formatter you can’t tell it not to do that without using ugly hacks.
Sure, logically there are times when you don’t need them. But, often it helps to explain what’s happening in the code when you can use parentheses to group certain things. It helps in particular when you want to use “&&” and “||” to say “do X only if Y fails”.
I think you can do
// prettier-ignore, because I remember facing that exact situation.
I sometimes like to add unnecessary parentheses or brackets to section things off and improve legibility, but I don’t do any math stuff collaboratively, so I have no idea whether others would find that disruptive or helpful.
I do this, sometimes it helps reveal a natural pattern when some parts of earlier terms have “disappeared” to simplification
I mean, there are very few ambiguous cases when you know how the order of operations works.
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The high-and-mightiness quotient in this thread is reaching critical levels
it’sa badlywrittenmathproblemSeriously, every time this comes up and everyone makes a huge deal out of it, I keep thinking, “none of the people writing these better be teachers.” You have to be more clear than this.
Edit: ok, not so much this one. I just read the words and assumed the math problem was one of the ambiguous ones. Stand down, soldiers.
no
it’s
fucking
not
This is just basic algebra, this is actually how the problems in algebra I are written. What the fuck?
Whoa, you went from 0 to 100 on rage super quick. You ok buddy?
Not this one, there is no ambiguity here. Order of operations are all good.
You’re right. I honestly just assumed it was one of those intentionally engagement-baiting posts when I saw it and didn’t even process the problem itself.
how should it have been written?
Nope, you’re right. I just read the words and assumed it was one of the terrible ones.
This one is just…math.
I think it’s reasonable if you consider the kind of physical situation it might represent.
You visit a farm and there are 2 unpackaged apples. There are also 5 packages that hold 8 apples but 5 have been removed from each. How many apples are there?
In fairness, this one isn’t nearly as bad as most of the ambiguous problems that get passed around on Facebook with multiple parentheticals and such.
Your word problem is excellent.
But 2 + 5 + 8 - 5 is 16 - 5 which is 11
Parentheses first then Division or Multiplication then add or subtract. PEDMAS
8-5= 3
3*5=15
15+2=17
Gotta distribute:
2+(8+5)-(5+5)
2+13-0
15
Still not how distribution works. That would be:
2+((8 * 5)-(5 * 5))
2+(40-25)
2+(15)
17
Anything other than 17 is wrong. No matter how you go about your multiplication step.
You’re trolling, but no, if you distribute you get the same result:
2 + 5(8 - 5) =
2 + (5 × 8) + (5 × -5) =
2 + (40) + (-25) =
2 + 40 - 25 = 2 + 15 = 17
This is an antimeme
Lot of people seeming to miss that point here!
Hrmm.
I read that as resulting in 21.
My education system did fail me.
I plugged that into ghci as 2+5*(8-5), and it says 17.
:(
I did (2+5)*(8-5).
Doh.
[Edit: (Double doh! Mistyped that here as 5+2. XD)]
I did (2+5)*(8-5).
The problem is you can’t just add parenthesis willy nilly, that breaks the whole equation!
Well, it used to be a free country until common core and now this nonsense is the result. Numbers and punctuation mixed together. Pure chaos.
You do parenthesis first and then multiplications and then sums, you did parenthesis, then sums, then multiplications, wich is wrong.
You don’t necessarily have to do parentheses first. What matters is that the things inside the parentheses are a group that you can’t break apart. If you have
10÷2+3-2*(2+1)you can do the division first5+3-2*(2+1)then the addition outside the parentheses8-2*(2+1)It’s just that before you do the multiplication of the term outside the parentheses, you have to handle the parentheses group, so you get8-2*3->8-6->2
plugged that into ghci as 5+2*(8-5), and it says 17.
You might want to report that error. Or, did you mean 2+5*(8-5)?
Oops! Typo. School failed me hard!
[Edit: Thanks. Corrected that.]
How far along in school are you btw?
To all the people yelling PEMDAS and BOMBDAS or whatever - languages other than English exist.
In French there’s no acronym. We just learn it. It’s not that hard.
It’s not like “PEMDAS” is easy to remember, as “Pemdas” as word does not exist.
We didn’t have anything to remember it by either, you just learn the order of operations and that’s it.
Works the same in Swedish. 👌
Meneer Van Dale Wacht Op Antwoord (Exponents, multiplication, division, root, addition, subtraction in Dutch).
Wait is Antwoord the same meaning in Afrikaans? Does the name of the band Die Antwoord literally mean The Subtraction?
I wrote the Dutch mnemonic not the actual Dutch word for multiplication etc. The letters of that mnemonic stands for “machtsverheffen”, “vermenigvuldigen”, “delen”, “worteltrekken”, “optellen”, “aftrekken”.
Also “Antwoord” is “answer” in Dutch and Afrikaans.
Just rolls off the toungue
Die Klammer sagt: „Erst komme ich!“ dann gilt die Regel „Punkt vor Strich“
KlaPuStri
Klammer, Punkt, Strich?
IT’S PEMBDURRS
KlaHoPS
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Math isn’t flexible like that though. You’re asking for flexibility where there is none. Sure pemdas is technically arbitrary but having a set convention for that is strictly necessary and good teaching.
Not understanding the logic doesn’t mean it doesn’t exist.
We created math and devised a method to ensure that equations can be solved in a way that leads everybody to the same result. If you don’t use the rule, you don’t get the same answer as someone who does. In this circumstance, yes, you do teach by nailing down a strict rule as it’s foundational to the language (math) that we’ve created.
But there is logic behind them.
1+2+3=6 and 2+3+1=6 also.
But 1+2*3 and 2*3+1 won’t come out the same if you do the calculations in just any order. It’s not always possible to order them left to right like in the second version, and if we use parentheses for everything we can end up with an illegible mess. I actually tried to type an example of how silly it could look and lost track of my own parentheses nesting before I got very far.
Do you have any other suggestion for how to notate an equation which would make memorization of PEMDAS unnecessary?
🤨
Bro doesn’t know how math works
I’m not seeing a single mention of My Dear Aunt Sally. The youth are lost…
You’re drunk Sally, go to bedmas!
Aunt Sally said some racist things at Thanksgiving, I’m tired of excusing her smh
Already saying racist things this early in the morning? (It’s Thanksgiving in the US today)
I’ll never understand these approaches to learning. They require remembering the phrase, and then require remembering how the phrase translates to the rules you need to remember.
I’ll just remember the rules in the first place. Less effort.
There’s just no way rote learning is easier than mnemonics unless you have a photographic memory.
Shit, I still remember the order of taxonomic ranks after seeing the phrase “King Phillip came over from Germany stoned” written in a used bio textbook 30 years ago when we never even made it to that chapter to officially study in class. I guarantee I never would’ve remembered the list “kingdom phylum class order family genus species”.
Don’t ask anyone over the age of 45 how they remember resistor color codes …
Yeah, but there is more to remember. I remember BODMAS and if I forget the rules, I work it out and apply it.
