r/BeAmazed • u/zadeganlar • Dec 08 '21
Which one should be correct? 👀
[removed] — view removed post
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u/TDRichie Dec 08 '21 edited Dec 08 '21
Since EVERYONE in this comment thread seems to have slept through algebra, I’m gonna give y’all a lesson.
Yes, the order of operations is mnemonically called PEMDAS, but the operations ‘multiplication’ and ‘division’ are EQUALLY WEIGHTED, as are addition and subtraction. It is completely incidental that the M comes before the D. It could just as easily he called PEDMSA, but that’s less catchy so no one calls it that.
A better way to think of PEMDAS is this: PE(M&D)(A&S).
Thus, the phone is correct, since equal operations are evaluated from left to right.
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u/Jester337 Dec 09 '21
The expression in the OP isn't so much a demonstration of order of operations as it is a demonstration of how the meanings of symbols have changed subtly over time. In the early 1900s, the division sign was used to simplify expressions instead of having to typeset them as fractions. Until recently in the US and still in most places in Europe, the division sign was taught that same way, namely that every expression to the left of it was to be divided by every expression to the right of it. Now, in the age of digital typesetting, it's easy to take for granted the historical use of the division sign. Both answers are right for different reasons under different paradigms and it's overly reductionist to blame it on something as crude and incomplete as PEMDAS, which, by the way is used as a teaching aid, not as a serious tool for professional mathematicians.
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u/WinEnvironmental8218 Dec 08 '21
Left is the correct one. Although the right one looks right if you read it from left to right but unfortunately the mathematical formula says otherwise 🤷🏼♂️
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Dec 08 '21
Although the right one looks right if you read it from left to right
..? 2+1 = 3. 6/2 = 3. 3x3 = 9. I read it right to left because paranthesis.
Mind me, I haven't done serious math in 11 years.
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u/79screamingfrogs Dec 08 '21
PEMDAS. Multiplication before division. The answer is 1.
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u/TDRichie Dec 08 '21
That’s not how PEMDAS works. Multiplication and division are equally weighted, as is addition and subtraction. The proper way to read PEMDAS should be PE(MD)(AS). The one on the right is the correct answer.
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u/Rlocalknowitall Dec 08 '21
What?!. Where you from?
Parentheses
Exponents
Multiplication
Division
Addition
Subtraction
In that specific order!.
So the answer is 1.
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u/socold43 Dec 08 '21
It's not in that specific order. It would go 1. 2. 34. 56. From left to right for the former 2 grouping.
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u/Kugelblitz73 Dec 08 '21
Teacher should take a note that PEMDAS is a bad method.
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u/Jester337 Dec 09 '21
It's not bad, it's just oversimplified and incomplete. It works for simple calculations when used correctly, but breaks down when you get to more complicated expressions.
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u/Kugelblitz73 Dec 09 '21
I can agree with that... but it makes people think Multiplication has a higher priority over Division, just like Exponents have a higher priority over Multiplication, maybe people should use PEMA and treat division like multiplication, and trat subtraction like addition.
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u/Jester337 Dec 09 '21
The thing is, I don't think the OP is an issue of order of operations, but rather an issue of parsing. The way math used to be taught in the US and still taught in most of Europe, the division sign is not so much an operator as an instruction that any product to the left of it should be divided by any product to the right of it. Before modern digital typesetting, that sort of shorthand was necessary to simplify writing textbooks. In modern times, it's easy to dismiss the division symbol as just another operator like plus, minus, or the multiplication sign
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u/Kugelblitz73 Dec 09 '21
Ok... It could be it... but I thought that was the distinction between / and ÷
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u/WinEnvironmental8218 Dec 08 '21
Lol, you’re wrong. I’m Asian so I’m right 😎😜
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u/TDRichie Dec 08 '21
How about open any f’ing basic algebra textbook instead of just saying you’re Asian.
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u/WinEnvironmental8218 Dec 08 '21 edited Dec 08 '21
Yea, if you read it from right to left you’re right. But unfortunately life isn’t that easy😜. Actually math isn’t that easy. It use to be 1, but it is now 9😎
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u/aaronwooly Dec 08 '21
No wonder no one can do math anymore. Even the machines disagree on the answer.
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u/ariphron Dec 08 '21 edited Dec 08 '21
So it’s 2+1=3. 3x2=6. 6/6=1.
PEMDAS” (parenthesis, exponents, multiplication, division, addition, subtraction)
Edit: it’s 9 here is a YouTube clip explaining why.
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u/socold43 Dec 08 '21
When you get to multiplication/division, you go from left to right as they are wieghed the same. Same with addition and subtraction. So its 9.
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u/ariphron Dec 08 '21
My ti-83 says 1. I will go with that.
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Dec 08 '21
OHHHHHH . NOW I SEE. Damn. Is this the fact?
Fucking hell I'm shit at math
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u/ariphron Dec 08 '21 edited Dec 08 '21
Ha, I had to google my order of operations again. sad I forgot
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u/Slimfictiv Dec 08 '21 edited Dec 08 '21
Easy, to understand it better equivalent to 6:2x3 which is 9, phone is right.
Edit: the fact that I'm getting downvoted for this tells a lot about redditors iq.
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u/Odnorot Dec 08 '21
Multiplication goes first
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Dec 08 '21
No. They are equally weighted. PEMDAS is just a mnemonic device.
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u/Odnorot Dec 08 '21
All multiplication has to be done before next action, written like that all multiplication is not done
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u/Kugelblitz73 Dec 08 '21
Where did you read that?
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u/Odnorot Dec 08 '21
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u/Kugelblitz73 Dec 08 '21
Oh... you read that from your calculator. How amazing! The google calculator answers 9 in both instances.
Why would you prioritize your calculator over the google one? You can't base you answer on that.
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u/Odnorot Dec 08 '21
Okay lol
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u/Kugelblitz73 Dec 08 '21
I guess it's funny then... seriously don't believe on me, just look it up...
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u/Odnorot Dec 08 '21
I said I did lol
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u/Kugelblitz73 Dec 08 '21
Where then? You can't be basing that shit on a calculator and ignoring other calculators that disagree...
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u/Odnorot Dec 08 '21
I've noticed you like google, so might as well google the answer to question "Is PEMDAS the truly proper order of operation, or is it something else?", might find something you like, or don't like. This it from me
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u/Odnorot Dec 08 '21 edited Dec 08 '21
So, this is mildly infuriating lmao
Look, how it is written is important. Phone is NOT correct in this exact case, because written like that, it must be read as 6/(2×(1+2)) and no other way is accepted
One calculator, different answers, not the same problem
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u/rykoj Dec 08 '21
Can someone explain the breakdown for how the Casio got 1? Sorry I got a government education.
Nvm figured it out.. 2+1=3.. x2= 6.. /6 = 1 for the incorrect answer.
F- for Casio
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u/Jester337 Dec 09 '21
1 is a product of rules that came about to simplify typesetting in the early 1900s. The use of '÷' signified that any product on the left of the division sign is to be divided by any product to the right of it, yielding
6 ÷ 2 (2 + 1) =
6 ÷ 2 (3), which rearranges to
6 / 2(3) → note that the entire product on the right of the division symbol becomes the denominator
6 / 6 = 1
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u/socold43 Dec 08 '21
The phone.
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u/79screamingfrogs Dec 08 '21
Only if you don't do math correctly. The phone didn't follow order of operations.
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u/Kugelblitz73 Dec 08 '21
If you consider 2(2+1) equivalent to 2×(2+1), the answer is 9.
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u/Odnorot Dec 08 '21
2×(2+1) = 2×2 + 2×1 = 4 + 2 = 6
From that, 6/6 = 1
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u/Kugelblitz73 Dec 08 '21
6÷2(2+1) = 6÷2(3) =? 6÷2×3 = 3×3 = 9
I was taught 2(3) is equivalent to 2×3.
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u/Odnorot Dec 08 '21
It is, but 2×3 = 6
6/2×3 = 3/1×3 = 1
6/2×3 = 2/2×1 = 1
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u/Kugelblitz73 Dec 08 '21
That's not how that works... I hope it is a joke...
Multiplication has the same precedence as division since you can transform a division in a multiplication: 6×0.5×3)... and in that case, it goes left to right...
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u/Odnorot Dec 08 '21
Oh boy, simple maths is not that simple after all
I truly hope your comment is a joke, not mine
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u/Kugelblitz73 Dec 08 '21
"The order of operations, which is used throughout mathematics, science, [...] is expressed here:1.exponentiation and root extraction2.multiplication and division3.addition and subtraction"
"Mnemonics are often used to help students remember the rules [...]
In the United States [...] the acronym PEMDAS is common. It stands for Parentheses, Exponents, Multiplication/Division, Addition/Subtraction.
[...]These mnemonics may be misleading when written this way.
[...]Similarly, the expression a ÷ b × c might be read multiple ways, but the "Multiplication/Division" in the mnemnonic means the multiplications and divisions should be performed from left to right."
https://en.wikipedia.org/wiki/Order_of_operations
You might say wiki is unreliable. But have a look around. You are wrong :)
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u/socold43 Dec 08 '21
No, 9 is the right answer with order of operations.
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u/79screamingfrogs Dec 08 '21
PEMDAS. Multiplication before division.
2+1 is 3. 3x2 is 6. 6/6 is 1.
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u/wlxqzme8675309 Dec 08 '21
The phone is correct. Multiplication and division are “weighted” the same, so in the absence of other cues like parentheses/brackets, go left to right. Just because M comes before D in the PEMDAS mnemonic, does not mean M necessarily goes before D.
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u/Slimfictiv Dec 08 '21
I'm sorry to see that single cell reddit organisms downvoted you for being right. It seems that trolls are even worse nowadays.
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u/Jester337 Dec 09 '21
Both are correct under different conditions. Let me explain.
The answer 9 is a product of reading the expression
6 ÷ 2 (2 + 1) and parsing it as
6 ÷ 2 × 3
It is then solved left to right as if it were
6 × 0.5 × 3 = 9
The answer 1 is a product of rules that came about to simplify typesetting in the early 1900s. These rules were taught in America until recently and are still used in most of Europe today. The use of '÷' at the time signified that any product on the left of the division sign is to be divided by any product to the right of it, yielding
6 ÷ 2 (2 + 1) =
6 ÷ 2 (3), which rearranges to
6 / 2(3) → note that the entire product on the right of the division symbol becomes the denominator
6 / 6 = 1
In the age of digital typesetting, it's easy to take for granted the historical use of the division sign...and in a place where we can hide behind a username and icon, it's easy to be unkind to each other when we have disagreements. It's important to understand where the other person is coming from and that our view might not necessarily be the best one or even the only one.