I dunno (piefed.cdn.blahaj.zone)
 
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[–] 323 points 11 months ago (113 children)

I feel like I am getting trolled

Isn't 17 the actual right answer?

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  • [–] 162 points 11 months ago (7 children)
  • [–] 128 points 11 months ago (6 children)

    So it's just an unfunny meme?

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  • [–] 101 points 11 months ago (1 child)

    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.

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  • [–] 36 points 11 months ago (42 children)

    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.

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  • [–] 10 points 11 months ago* (25 children)

    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.

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  • [–] 8 points 11 months ago* (last edited 11 months ago) (10 children)

    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 = 3 + 2 + 1

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  • [–] 4 points 11 months ago (3 children)

    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.

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  • [–] 4 points 11 months ago (1 child)

    something has to be the rule for processing it

    Well the rule is: any order goes. Summation is commutative.

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  • [–] 4 points 11 months ago*

    No, you completely misunderstood my point. My point is not to describe all valid interpretations of the commutative property, but the one most slow kids will hear.

    OFC the actual rule is the order doesn't matter, but kids that don't pick up on the nuance of the commutative property will still remember, "order of appearance is fine".

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  • [–] 2 points 11 months ago (3 children)

    You flipped the sign on the 3 and 1.

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  • [–] 5 points 11 months ago (11 children)

    PE(MD)(AS)

    Now just remember to account for those parentheses first...

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  • [–] 3 points 10 months ago* (last edited 10 months ago) (7 children)

    Uh, no. I don't think you've thought this through, or you're just using (AS) without realizing it. Conversations around operator precedence can cause real differences in how expressions are evaluated and if you think everyone else is just being pedantic or is confused then you might not underatand it yourself.

    Take for example the expression 3-2+1.

    With (AS), 3-2+1 = (3-2)+1 = 1+1 = 2. This is what you would expect, since we do generally agree to evaluate addition and subtraction with the same precedence left-to-right.

    With SA, the evaluation is the same, and you get the same answer. No issue there for this expression.

    But with AS, 3-2+1 = 3-(2+1) = 3-3 = 0. So evaluating addition with higher precedence rather than equal precedence yields a different answer.

    =====

    Some other pedantic notes you may find interesting:

    There is no "correct answer" to an expression without defining the order of operations on that expression. Addition, subtraction, etc. are mathematical necessities that must work the way they do. But PE(MD)(AS) is something we made up; there is no actual reason why that must be the operator precedence rule we use, and this is what causes issues with communicating about these things. People don't realize that writing mathematical expressions out using operator symbols and applying PE(MD)(AS) to evaluate that expression is a choice, an arbitrary decision we made, rather than something fundamental like most everything else they were taught in math class. See also Reverse Polish Notation.

    Your second example, -1+3+2=4, actually opens up an interesting can of worms. Is negation a different operation than subtraction? You can define it that way. Some people do this, with a smaller, slightly higher subtraction sign before a number indicating negation. Formal definitions sometimes do this too, because operators typically have a set number of arguments, so subtraction is a-b and negation is -c. This avoids issues with expressions starting with a negative number being technically invalid for a two-argument definition of subtraction. Alternatively, you can also define -1 as a single symbol that indicates negative one, not as a negation operation followed by a positive one. These distinctions are for the most part pedantic formalities, but without them you could argue that -1+3+2 evaluated with addition having a higher precedence than subtraction is -(1+3+2) = -6. Defining negation as a separate operation with higher precedence than addition or subtraction, or just saying it's subtraction and all subtraction has higher prexedence than addition, or saying that -1 is a single symbol, all instead give you your expected answer of 4. Isn't that interesting?

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  • [–] 2 points 10 months ago* (3 children)

    Oh, it's you. I really want to have a good discussion about this, but it is not possible with your debate style. Once again, fragmenting your opponent's argument into a million partial statements and then responding to those is ineffective for several reasons:

    1. You fail to understand the argument your opponent is making, and so you do not learn anything by engaging with it. You must first understand to learn.

    2. By divorcing each partial statement from its surrounding context, you are likely to change its meaning, so you are no longer even responding to the meaning of what was said.

    3. You are not making a point of your own, which means you are less likely to figure out your own mental model. You are simply stating facts, opinions, or misunderstandings as if they are self-evidently true, without knowing why you believe them to be true.

    4. Expanding on point three, it's very easy to state two contradictory things without realizing it. For example, "No they can’t. The rules are universal" and "It’s only a convention, not a rule, as just proven".

    5. Also expanding on point three, this also makes it hard for people to find the mistakes you're making and correct them, because mistakes in your mental model are only visible through the statements you choose to make, which are incoherent when taken together. For example, I can see that you don't fully understand what I mean by "operator precedence", but this is not obvious from your main point, because you have no main point, because you do not understand what mine is.

    6. If your opponent also used this debate style, the argument takes hours and ends up entirely divorced from the initial meaning, completely destroying any hope of having the debate provide any actual value, ie. greater understanding.

    Please do not take these as insults; it's a long shot to fundamentally change someone's perspective like this in one post, but I would love if you saw the beauty of discussion. To bring it back to your original comment:

    Those Brackets don’t matter. I don’t know why people insist it does

    Understanding the purpose and methods of debate allows you to understand why people know the brackets matter.

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  • [–] 2 points 10 months ago* (last edited 10 months ago) (1 child)

    I'm falling for the troll here but I feel compelled to point out that you did NOT read the post I deleted lmao. I deleted it because I posted it before you "responded" to my points. Go check it out, I just restored it.

    I should clarify that I haven't responded to your "points" because there is nothing worth responding to. Your arguments can all be debunked by reading https://en.wikipedia.org/wiki/Order_of_operations, so I didn't bother doing it myself.

    To avoid any further temptation to respond I will be blocking you. Your absence from my future will be greatly appreciated. I feel that the deleted post is in itself a very good final word to this disappointment of a "conversation" even if it is not entirely accurate. Goodbye.

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  • [–] 2 points 11 months ago

    Huh I just remembered the orders of arithmetic but parentheses trump all so do them first (I use them in even the calculator app). Mean I assume that's that that says but never learned that acronym is all. Now figuring out categories of words;really does my noodle in sometimes. Cause some words can be either depending on context. Math when it's written out has (mostly) the same answer. I say mostly because somewhere in the back of my brain there are some scenarios where something more complicated than straight arithmetic can come out oddly but written as such should come out the same.

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  • [–] 3 points 10 months ago

    Save yourself the trouble - Smartman Apps is a crank. They categorically will not comprehend the difference between the notation we made up and how numbers work. Dingus keeps saying 'animals can count' like that proves parentheses-first is completely different! from distribution.

    Why'd Russel and Whitehead bother with the Principia Mathematica when they could just point to Clever Hans?

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  • [+] 9 points 11 months ago (58 children)
  • [–] 21 points 11 months ago (57 children)

    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.

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  • [–] 6 points 11 months ago* (last edited 11 months ago) (52 children)

    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 + d
    

    Or (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
        -
        c
    

    Is much more common and useful. So people get used to grouping everything around the division operator as if they're in parentheses.

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  • [–] 4 points 11 months ago (30 children)

    Or
    12 / 2(6)
    And trying to argue this is 36.

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  • [–] 5 points 11 months ago

    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.

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  • [–] 7 points 11 months ago (20 children)

    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 from ab and/or a × b.

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  • [–] 4 points 10 months ago* (last edited 10 months ago) (18 children)

    Please read this section of Wikipedia which talks about these topics better than I could. It shows that there is ambiguity in the order of operations and that for especially niche cases there is not a universally accepted order of operations when dealing with mixed division and multiplication. It addresses everything you've mentioned.

    https://en.wikipedia.org/wiki/Order_of_operations#Mixed_division_and_multiplication

    There is no universal convention for interpreting an expression containing both division denoted by '÷' and multiplication denoted by '×'. Proposed conventions include assigning the operations equal precedence and evaluating them from left to right, or equivalently treating division as multiplication by the reciprocal and then evaluating in any order;[10] evaluating all multiplications first followed by divisions from left to right; or eschewing such expressions and instead always disambiguating them by explicit parentheses.[11]

    Beyond primary education, the symbol '÷' for division is seldom used, but is replaced by the use of algebraic fractions,[12] typically written vertically with the numerator stacked above the denominator – which makes grouping explicit and unambiguous – but sometimes written inline using the slash or solidus symbol '/'.[13]

    Multiplication denoted by juxtaposition (also known as implied multiplication) creates a visual unit and is often given higher precedence than most other operations. In academic literature, when inline fractions are combined with implied multiplication without explicit parentheses, the multiplication is conventionally interpreted as having higher precedence than division, so that e.g. 1 / 2n is interpreted to mean 1 / (2 · n) rather than (1 / 2) · n.[2][10][14][15] For instance, the manuscript submission instructions for the Physical Review journals directly state that multiplication has precedence over division,[16] and this is also the convention observed in physics textbooks such as the Course of Theoretical Physics by Landau and Lifshitz[c] and mathematics textbooks such as Concrete Mathematics by Graham, Knuth, and Patashnik.[17] However, some authors recommend against expressions such as a / bc, preferring the explicit use of parenthesis a / (bc).[3]

    More complicated cases are more ambiguous. For instance, the notation 1 / 2π(a + b) could plausibly mean either 1 / [2π · (a + b)] or [1 / (2π)] · (a + b).[18] Sometimes interpretation depends on context. The Physical Review submission instructions recommend against expressions of the form a / b / c; more explicit expressions (a / b) / c or a / (b / c) are unambiguous.[16]

    Image of two calculators getting different answers 6÷2(1+2) is interpreted as 6÷(2×(1+2)) by a fx-82MS (upper), and (6÷2)×(1+2) by a TI-83 Plus calculator (lower), respectively.

    This ambiguity has been the subject of Internet memes such as "8 ÷ 2(2 + 2)", for which there are two conflicting interpretations: 8 ÷ [2 · (2 + 2)] = 1 and (8 ÷ 2) · (2 + 2) = 16.[15][19] Mathematics education researcher Hung-Hsi Wu points out that "one never gets a computation of this type in real life", and calls such contrived examples "a kind of Gotcha! parlor game designed to trap an unsuspecting person by phrasing it in terms of a set of unreasonably convoluted rules".[12]

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  • [–] 4 points 10 months ago (16 children)

    If you believe the article is incorrect, submit your corrections to Wikipedia instead of telling me.

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  • [–] 2 points 10 months ago (14 children)

    Again, if you have a problem with Wikipedia, take it up with Wikipedia.

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  • [–] 2 points 10 months ago (12 children)

    Take it up with them if you have a problem with them.

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  • [–] 2 points 10 months ago (8 children)

    I haven't ignored anything you said. I'm telling you that if you have a problem with those that you should contact them to fix them.

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  • [–] 2 points 10 months ago (6 children)

    It's funny that you define "ignore" as "not doing what you tell someone to" because by that definition you've been ignoring me too. Go edit the article if you feel this strongly.

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  • [–] 3 points 11 months ago (7 children)

    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

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  • [–] 2 points 10 months ago* (5 children)

    Are you under the impression that atomizing your opponents statements and making a comment about each part individually without addressing the actual point (how those facts fit together) is a good debate tactic? Because it seems like all you've done is confuse yourself about what I was saying and make arguments that don't address it. Never mind that some of those micro-rebuttals aren't even correct.

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  • [–] 2 points 10 months ago (14 children)

    Take it up with Berkeley then.

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  • [–] 2 points 10 months ago (10 children)

    I cannot stress this enough. If you have a problem with that, contact the author or Berkeley, not me.

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  • [–] 2 points 10 months ago (6 children)
  • [–] 2 points 10 months ago (4 children)

    You can stop humoring this broken robot. Especially when the context is 'yeah I already said this textbook is wrong, but I am better than you because you need to read this textbook.'

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  • [–] 2 points 10 months ago (3 children)

    They seem to believe that and on the 8th day God made the one true objective order of operations that all humans use and agree on.

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  • [–] 2 points 10 months ago* (2 children)

    Except for that time the definition of division changed 130 years ago. Which is not a rule! It's notation, or syntax, or possibly sometimes a rule. Whichever one lets them sneer hardest.

    I tried explaining RPN to them a year ago. They still insist there's parentheses in it. Today they called it an "app."

    Dogmatic patience vampire is still trying to bait me into further wasted effort.

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  • [–] 2 points 10 months ago (1 child)

    Wowww. Insisting that they're good at math. I distinctly remember learning that RPN doesn't need parentheses in college.

    reverse Polish calculators do not need expressions to be parenthesized

    https://en.wikipedia.org/wiki/Reverse_Polish_notation

    But, you know, anyone can edit Wikipedia. Someone probably put that there who hasn't opened a math textbook.

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  • [–] 2 points 10 months ago

    Oh of course. The sky isn't blue unless that's written in a maths textbook.

    And if you look up and see stars, it's still blue, because it's written in a maths textbook! Are you saying a teacher could be wrong?!, smug emoji, crying emoji, roll-eyes emoji?

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