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I don’t get why these kind of post crop up so often.
The answer to them doesn’t matter and these aren’t really math questions, because there is no context given. This is just endless discussions about different people having different assumptions on notation used there…
In real math, where the numbers mean something, good and consistent notation is important, but not necessary, because the order of operations or what those operations are exactly would be clear through the context of these formulas. Good notation just makes it easier to spot errors, work with formulas or to avoid confusion.
Here is what I would assume this formula could mean. Someone has 2 apples and 5 bags of apples that initially came with 8 apples each inside, but someone else ate 5 apples from each of these bags.
With this context it is pretty clear what the answer would be.
Any PEMDAS enjoyers in chat?
2+5(8-5)
For anyone wanting to see a different way of solving it with distribution:
2+58-55 2+40-25 42-25 17
So long as you follow the basic math rules, you can solve it in many different ways to get the same result.
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 ) ) )So, if
2 5 8 5 - × +is “RPN” does that mean that the LISP version is Polish Notation?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.
Also, you can use this for more than just arithmetic. The first thing in the list is the name of the function, and everything else is something that you pass to the function. So you could instead write
(plus 1 2 3 4)Which would be like
plus(1, 2, 3, 4)in other kinds of programming languages.I understand prefix notation, but you got the order of operations wrong…
Yeah I’m stupid
Knowing is half the battle!
Awesome thanks for explaining that. That’s cool as hell.
Pemdas, parenthesis first, for a total of 3. Then multiplication, 15, then addition. 17. What’s hard about this?
What’s hard about it is people are fucking stupid.
you go the other direction below the equator
Isn’t the southern hemisphere above the equator if you live there
depends if you are normal or planar in ENU coordinates
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?
It became a meme a few years ago, people would post problems like this and argue about whose was right, as if there were no objective truth. It hurt to watch.
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.
Probably some backwards-ass red state / red town shenanigans.
Math was always taught in my Blue cities. The atrocities of the US’s history was never left out of the curriculum.
We need to actually finish doing reconstruction and fix this country.
Definitely taught in parts of the US, it’s a regional thing though
I think that ordering of calculation was taught around 5th grade back in my day (11yo)
In most of the world? Yes.
We didn’t learn elements until high school tbf
2+5 is 8, 8-5 is 3. 8×3 is 24.
But I also haven’t done this kind of math since 4th grade so I’m not sure if the joke is that this is the real answer or the answer you get doing it wrong… 🤔
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2+5=8 quick maths (please don’t fix it, thanks. Hope you’re having a good one)
BEDMAS
do it in the order of brackets, exponents, division, multiplication, addition, and subtraction.
So, brackets: (8-5) is 3, Multiplication: 3×5 is 15, addition: 15+2 is 17.
It’s 8-5
Just noticed and fixed that a split second before your reply. We didnt have the mnemonic when I was going to school. Though I almost guarantee I would remember “PEMDAS” but not what it stood for even if we did 🤣
Are you trolling? The bracket says (8-5) not (8-3)
You probably have to wait a moment for the edit to federate.
Ahhh ok now i see it, sorry :)
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 .
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’ve done that, but that’s ugly.
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!
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?
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?
