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(* (+ 2 5) (- 8 5))Hope some LISP can clear this up
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.
it’s
a badly
written
math
problem
Seriously, 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.
Pemdas, parenthesis first, for a total of 3. Then multiplication, 15, then addition. 17. What’s hard about this?
Some other parent’s thesis.
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
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.
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
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 .
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.
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
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.
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.
Works the same in Swedish. 👌
Meneer Van Dale Wacht Op Antwoord (Exponents, multiplication, division, root, addition, subtraction in Dutch).
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.
I feel like I am getting trolled
Isn’t 17 the actual right answer?
Some people insist there’s no “correct” order for the basic arithmetic operations. And worse, some people insist the correct order is parenthesis first, then left to right.
Both of those sets of people are wrong.
Hopefully you can see where their confusion might come from, though. PEMDAS is more P-E-MD-AS. If you have a bunch of unparenthesized addition and subtraction, left to right is correct. A lot of like, firstgrader math problems are just basic problems that are usually left to right (but should have some extras to highlight PEMDAS somewhere I’d hope).
So they’re mostly telling you they only remember as much math as a small child that barely passed math exercizes.
If you have a bunch of unparenthesized addition and subtraction, left to right is correct
If you have a bunch of unparenthesized addition and subtraction, left to right doesn’t matter.
1 + 2 - 3 = 1 - 3 + 2 = -3 + 2 + 1
True, but as with many things, something has to be the rule for processing it. For many teachers as I’ve heard, order of appearance is ‘the rule’ when commutative properties apply. … at least until algebra demands simplification, but that’s a different topic.
PE(MD)(AS)
Now just remember to account for those parentheses first…
Exactly
So it’s just an unfunny meme?
I think it’s meant to play with your expectations. Normally someone’s take being posted is to show them being confidently stupid, otherwise it isn’t as interesting and doesn’t go viral.However, because we’re primed to view it from that lens, we feel crazy to think we’re doing the math correctly and getting the “wrong answer” from what we assume is the “confident dipshit”.
There’s layers beyond the superficial.
I fell for it. It’s crazy to think how heavily I’ve been trained to believe everything I see is wrong in the most embarrassing and laughable way possible. That’s pretty depressing if you think about it.
As most memes are.
Not even a meme.
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Yeah I know that. But I was feeling confused as to why it was here. That’s why I was feeling trolled, because it made me doubt basic math for being posted in a memes community.
Gotcha gotcha, sorry
They did the joke wrong. To do it right you need to use the ÷ symbol. Because people never use that after they learn fractions, people treat things like a + b ÷ c + d as
a + b ----- c + dOr (a + b) ÷ (c + d) when they should be treating it as a + (b ÷ c) + d.
That’s the most common one of these “troll math” tricks. Because notating as
a + b + d - cIs much more common and useful. So people get used to grouping everything around the division operator as if they’re in parentheses.
Or
12 / 2(6)
And trying to argue this is 36.Now that’s a good troll math thing because it gets really deep into the weeds of mathematical notation. There isn’t one true order of operations that is objectively correct, and on top of that, that’s hardly the way most people would write that. As in, if you wrote that by hand, you wouldn’t use the
/symbol. You’d either use ÷ or a proper fraction.It’s a good candidate for nerd sniping.
Personally, I’d call that 36 as written given the context you’re saying it in, instead of calling it 1. But I’d say it’s ambiguous and you should notate in a way to avoid ambiguities. Especially if you’re in the camp of multiplication like
a(b)being different fromaband/ora × b.Well, now you might be running into syntax issues instead of PEMDAS issues depending on what they’re confused about. If it’s 12 over 2*6, it’s 1. If it’s 12 ÷ 2 x 6, it’s 36.
A lot of people try a bunch of funky stuff to represent fractions in text form (like mixing spaces and no spaces) when they should just be treating it like a programmer has to, and use parenthesis if it’s a complex fraction in basic text form.
The P in PEMDAS means to solve everything within parentheses first; there is no “distribution” step or rule that says multiplying without a visible operator other than parentheses comes first. So yes, 36 is valid here. It’s mostly because PEMDAS never shows up in the same context as this sort of multiplication or large fractions
Alternatively, the poster calculated the wrong answer, thus assuming this guy was wrong.
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This shit take got deleted right in front of my eyes
The system works
Oh so just like me on !lemmyshitpost@lemmy.world
There is no answer. Because there is no question.
That is a problem, tho
I know the solution
