Saw it posted on Instagram or Facebook or somewhere and all of the top comments were saying 1. Any comment saying 16 had tons of comments ironically telling that person to go back to first grade and calling them stupid.
At this point, you solve it left to right because division and multiplication are on the same level. BODMAS and PEMDAS were created by teachers to make it easier to remember, but ultimately, they are on the same level, meaning you solve it left-to-right, so…
Under pemdas divisor operators must literally be completed after multiplication. They are not of equal priority unless you restructure the problem to be of multiplication form, which requires making assumptions about the intent of the expression.
Okay, let me put it in other words: Pemdas and bodmas are bullshit. They are made up to help you memorise the order of operations. Multiplication and division are on the same level, so you do them linearly aka left to right.
Pemdas and bodmas are not bullshit, they are a standard to disambiguate expression communication. They are order of operations. Multiplication and division are not on the same level, they are distinct operations which form the identity when combined with a multiplication.
Similarly, log(x) and e^x are not the same operation, but form identity when composited.
Formulations of division in algebra allow it to be at the same priority as multiplication by restructuring it as multiplication, but that requires formulating the expression a particular way. The ÷ operator however is strictly division. That’s its purpose. It’s not a fantastic operator for common usage because of this.
There are valid orders of operations, such as depmas which I just made up which would make the above expression extremely ambiguous. Completely mathematically valid, order of ops is an established convention, not mathematical fact.
I agree that pemdas is a bad acronym for teaching exactly because it can be misunderstood as multiplication coming before division and addition coming before substraction, when it’s not the case.
Luckily we don’t have that acronym where I grew up. We learned “dot before line” (as our division and multiplication symbols involve dots while the addition and substraction symbols only involve lines).
But that’s not the same thing as 8÷2(2+2). 2x(2+2) is 2 Terms, 2(2+2) is 1 Term. 8÷2×(2+2)=16 ((2+2) is in the numerator), 8÷2(2+2)=1 (2(2+2) is in the denominator)
And both you and people arguing that it’s 1 would be wrong.
This problem is stated ambiguously and implied multiplication sign between 2 and ( is often interpreted as having priority. This is all matter of convention.
I see what you’re getting at but the issue isn’t really the assumed multiplication symbol and it’s priority. It’s the fact that when there is implicit multiplication present in an algebraic expression, and really best practice for any math above algebra, you should never use the ‘÷’ symbol. You need to represent the division as a numerator and denominator which gets rid of any ambiguity since the problem will explicitly show whether (2+2) is modifying the numerator or denominator. Honestly after 7th grade I can’t say I ever saw a ‘÷’ being used and I guess this is why.
Back in gradeschool I was always taught that in Pemdas, the parenthesis are assumed to be there in 8÷(2×(2+2)) where as 8÷2×(2+2) would be 16, 8÷2(2+2) is the above and equals 1.
Not quite. It’s true you resolve what’s inside the parentheses first, giving you. 8÷2(4) or 8÷2x4.
Now this is what gets most people. Even though Multiplication technically comes before Division the Acronym PEMDAS, that’s really just to make it sound correct phonetically. Really they have equal priority in the order of operations and the appropriate way to resolve the problem is to work from left to right solving each multiplication or division sign as you encounter them. Giving you 16. Same for addition and subtraction.
So basically the true order of operations is:
Work left to right solving anything inside parentheses
Work left to right solving any exponentials
Work left to right solving any multiplication or division
Work left to right solving any addition or subtraction
Source: Mechanical Engineering degree so an unfortunate amount of my life spent in math and physics classes.
Absolutely, its all seen as equal so it has to go left to right However as I said in the beginning the way I was taught atleast, is when you see 2(2+2) and not 2×(2+2) you assume that 2(2+2) actually means (2×(2+2 )) and so must do it together.
Ah sorry just realized what you were saying. I’ve never been taught that. Maybe it’s just a difference in teaching styles, but it shouldn’t be since it can actually change the outcome. The way I was always taught was if you see a number butted up against an expression in parentheses you assume there is a multiplication symbol there.
So you were taught that 2(2+2) == (2(2+2))
I was taught 2(2+2)==2*(2+2)
Interesting difference though because again, assuming invisible parentheses can really change up how a problem is done.
Edit: looks like theshatterstone54’s comment assumed a multiplication symbol as well.
It’s true you resolve what’s inside the parentheses first, giving you. 8÷2(4) or 8÷2x4.
Not “inside parenthesis” (Primary School, when there’s no coefficient), “solve parentheses” (High School, The Distributive Law). Also 8÷2(4)=8÷(2x4) - prematurely removing brackets is how a lot of people end up with the wrong answer (you can’t remove brackets unless there is only 1 term left inside).
Under normal interpretations of pemdas this is simply wrong, but it’s ok. Left to right only applies very last, meaning the divisor operator must literally come after 2(4).
This isn’t really one of the ambiguous ones but it’s fair to consider it unclear.
Pemdas puts division and multiplication on the same level, so 34/22 is 12 not 3. Implicit multiplication is also multiplication. It’s a question of convention, but by default, it’s 16.
Your position is that you disagree with established maths. So you’re kind of a maths-flatearther with your own theories, I get it. But for most people that just summarizes to “being wrong”.
I don’t know what you’re on about with your distributive law thing. That just states that a*(b + c) = a*b + a*c, and has literally no relation to notation.
I wasn’t. I quoted Maths textbooks, and if you read further you’ll find I also quoted historical Maths documents, as well as showed some proofs.
I didn’t say the distributive property, I said The Distributive Law. The Distributive Law isn’t ax(b+c)=ab+ac (2 terms), it’s a(b+c)=(ab+ac) (1 term), but inaccuracies are to be expected, given that’s a wikipedia article and not a Maths textbook.
I did read the answers, try doing that yourself
I see people explaining how it’s not ambiguous. Other people continuing to insist it is ambiguous doesn’t mean it is.
If you read the wikipedia article, you would find it also stating the distributive law, literally in the first sentence, which is just that the distributive property holds for elemental algebra. This is something you learn in elementary school, I don’t think you’d need any qualification besides that, but be assured that I am sufficiently qualified :)
By the way, Wikipedia is not intrinsically less accurate than maths textbooks. Wikipedia has mistakes, sure, but I’ve found enough mistakes (and had them corrected for further editions) in textbooks.
Your textbooks are correct, but you are misunderstanding them. As previously mentioned, the distributive law is about an algebraic substitution, not a notational convention. Whether you write it as a(b+c) = ab + ac or as a*(b+c) = a*b + a*c is insubstantial.
About the ambiguity: If I write f^{-1}(x), without context, you have literally no way of knowing whether I am talking about a multiplicative or a functional inverse, which means that it is ambiguous. It’s correct notation in both cases, used since forever, but you need to explicitly disambiguate if you want to use it.
I hope this helps you more than the stackexchange post?
8÷2(2+2) comes out to 16, not 1.
Saw it posted on Instagram or Facebook or somewhere and all of the top comments were saying 1. Any comment saying 16 had tons of comments ironically telling that person to go back to first grade and calling them stupid.
Let’s see.
8÷2×(2+2) = 8÷2×4
At this point, you solve it left to right because division and multiplication are on the same level. BODMAS and PEMDAS were created by teachers to make it easier to remember, but ultimately, they are on the same level, meaning you solve it left-to-right, so…
8÷2×4 = 4×4 = 16.
So yes, it does equal 16.
Under pemdas divisor operators must literally be completed after multiplication. They are not of equal priority unless you restructure the problem to be of multiplication form, which requires making assumptions about the intent of the expression.
Okay, let me put it in other words: Pemdas and bodmas are bullshit. They are made up to help you memorise the order of operations. Multiplication and division are on the same level, so you do them linearly aka left to right.
Pemdas and bodmas are not bullshit, they are a standard to disambiguate expression communication. They are order of operations. Multiplication and division are not on the same level, they are distinct operations which form the identity when combined with a multiplication.
Similarly, log(x) and e^x are not the same operation, but form identity when composited.
Formulations of division in algebra allow it to be at the same priority as multiplication by restructuring it as multiplication, but that requires formulating the expression a particular way. The ÷ operator however is strictly division. That’s its purpose. It’s not a fantastic operator for common usage because of this.
There are valid orders of operations, such as depmas which I just made up which would make the above expression extremely ambiguous. Completely mathematically valid, order of ops is an established convention, not mathematical fact.
This comment is the epitome of being confidently wrong on the internet.
For one misinterpretation? Are you sure about that?
There was 3 misinterpretations - see my reply to them.
I made a hashtag for people #LoudlyNotUnderstandingThings :-)
No, they’re not.
Yes, they are.
In other words, they are the inverse operation of each other - welcome to why they have the same precedence.
It’s a mathematical fact.
Except they are and you are literally demonstrating why PEMDAS is shitty acronym.
We’re agreed that order of operations is a poorly taught subject and pemdas would benefit from revision.
I agree that pemdas is a bad acronym for teaching exactly because it can be misunderstood as multiplication coming before division and addition coming before substraction, when it’s not the case.
Luckily we don’t have that acronym where I grew up. We learned “dot before line” (as our division and multiplication symbols involve dots while the addition and substraction symbols only involve lines).
However as I demonstrated an order of operations in which mult is before div is valid.
In this case your dot before line still would result in the above expression being ambiguous, as well.
Not literally. It’s only a mnemonic, not the actual rules.
Yes, they are. Binary operators have equal precedence, and unary operators have equal precedence.
But that’s not the same thing as 8÷2(2+2). 2x(2+2) is 2 Terms, 2(2+2) is 1 Term. 8÷2×(2+2)=16 ((2+2) is in the numerator), 8÷2(2+2)=1 (2(2+2) is in the denominator)
And both you and people arguing that it’s 1 would be wrong.
This problem is stated ambiguously and implied multiplication sign between 2 and ( is often interpreted as having priority. This is all matter of convention.
I see what you’re getting at but the issue isn’t really the assumed multiplication symbol and it’s priority. It’s the fact that when there is implicit multiplication present in an algebraic expression, and really best practice for any math above algebra, you should never use the ‘÷’ symbol. You need to represent the division as a numerator and denominator which gets rid of any ambiguity since the problem will explicitly show whether (2+2) is modifying the numerator or denominator. Honestly after 7th grade I can’t say I ever saw a ‘÷’ being used and I guess this is why.
That said, I’ll die on a hill that this is 16.
Rest in peace
A matter of convention: true
Unless you specify you aren’t using pemdas, that’s generally the assumed order of ops.
This is not one of the ambiguous ones, but it’s certainly written to be. Multiplication does indeed have priority under pemdas.
False. Actual rules of Maths
There aren’t any ambiguous ones - #MathsIsNeverAmbiguous
No, they’re correct Order of operations thread index
It’s not ambiguous, there’s no such thing as implicit multiplication
…following the rules of Maths.
Back in gradeschool I was always taught that in Pemdas, the parenthesis are assumed to be there in 8÷(2×(2+2)) where as 8÷2×(2+2) would be 16, 8÷2(2+2) is the above and equals 1.
Not quite. It’s true you resolve what’s inside the parentheses first, giving you. 8÷2(4) or 8÷2x4.
Now this is what gets most people. Even though Multiplication technically comes before Division the Acronym PEMDAS, that’s really just to make it sound correct phonetically. Really they have equal priority in the order of operations and the appropriate way to resolve the problem is to work from left to right solving each multiplication or division sign as you encounter them. Giving you 16. Same for addition and subtraction.
So basically the true order of operations is:
Source: Mechanical Engineering degree so an unfortunate amount of my life spent in math and physics classes.
Absolutely, its all seen as equal so it has to go left to right However as I said in the beginning the way I was taught atleast, is when you see 2(2+2) and not 2×(2+2) you assume that 2(2+2) actually means (2×(2+2 )) and so must do it together.
That’s basically what I was taught, too.
Edit to add: Ha, I just realized how similar our usernames are. Neat! :)
Ah sorry just realized what you were saying. I’ve never been taught that. Maybe it’s just a difference in teaching styles, but it shouldn’t be since it can actually change the outcome. The way I was always taught was if you see a number butted up against an expression in parentheses you assume there is a multiplication symbol there.
So you were taught that 2(2+2) == (2(2+2))
I was taught 2(2+2)==2*(2+2)
Interesting difference though because again, assuming invisible parentheses can really change up how a problem is done.
Edit: looks like theshatterstone54’s comment assumed a multiplication symbol as well.
No, it means it’s a Term (product). If a=2 and b=3, then axb=2x3, but ab=6.
2(2+2)==(2*(2+2)). More precisely, The Distributive Law says that 2(2+2)=(2x2+2x2).
Not “inside parenthesis” (Primary School, when there’s no coefficient), “solve parentheses” (High School, The Distributive Law). Also 8÷2(4)=8÷(2x4) - prematurely removing brackets is how a lot of people end up with the wrong answer (you can’t remove brackets unless there is only 1 term left inside).
Yes, it’s The Distributive Law.
Under normal interpretations of pemdas this is simply wrong, but it’s ok. Left to right only applies very last, meaning the divisor operator must literally come after 2(4).
This isn’t really one of the ambiguous ones but it’s fair to consider it unclear.
Pemdas puts division and multiplication on the same level, so 34/22 is 12 not 3. Implicit multiplication is also multiplication. It’s a question of convention, but by default, it’s 16.
https://en.m.wikipedia.org/wiki/Order_of_operations
Incorrect, pemdas puts multiplication before division.
Only in the literaly order of the words.
It stands for “Parentheses, Exponents, Multiplication/Division, Addition/Subtraction”
Notice the “/” between multiplication and division instead of a comma? That means these have the same priority.
Well there’s the problem. I maintain this to be a mistake.
Ok. You could also maintain that 1 + 1 equals 3 if you wish. Either way you are simply wrong.
I don’t think you understand my position if that’s your takeaway.
Your position is that you disagree with established maths. So you’re kind of a maths-flatearther with your own theories, I get it. But for most people that just summarizes to “being wrong”.
And “Multiplication” refers literally to multiplication signs, of which there are none in this question.
I always thought pemdas was more like P/E/MD/AS with MD and AS occurring left to right
This is how I was taught, but also people don’t really use the ÷ symbol in algebra beyond like 6th grade
Yes they do, just pick up a high school Maths textbook (in a country which uses obelus rather than colon).
There’s no such thing as implicit multiplication. The answer is 1.
I don’t know what you’re on about with your distributive law thing. That just states that
a*(b + c) = a*b + a*c
, and has literally no relation to notation.And “math is never ambiguous” is a very bold claim, and certainly doesn’t hold for mathematical notation. For some simple exanples, see here: https://math.stackexchange.com/questions/1024280/most-ambiguous-and-inconsistent-phrases-and-notations-in-maths#1024302
No, The Distributive Law states that a(b+c)=(ab+ac), and that you must expand before you simplify.
Examples by people who simply don’t remember all the rules of Maths. Did you read the answers?
Please learn some math before making more blatantly incorrect statements. Quoting yourself as a source is… an interesting thing to do.
https://en.m.wikipedia.org/wiki/Distributive_property
I did read the answers, try doing that yourself.
I’m a Maths teacher - how about you?
I wasn’t. I quoted Maths textbooks, and if you read further you’ll find I also quoted historical Maths documents, as well as showed some proofs.
I didn’t say the distributive property, I said The Distributive Law. The Distributive Law isn’t ax(b+c)=ab+ac (2 terms), it’s a(b+c)=(ab+ac) (1 term), but inaccuracies are to be expected, given that’s a wikipedia article and not a Maths textbook.
I see people explaining how it’s not ambiguous. Other people continuing to insist it is ambiguous doesn’t mean it is.
If you read the wikipedia article, you would find it also stating the distributive law, literally in the first sentence, which is just that the distributive property holds for elemental algebra. This is something you learn in elementary school, I don’t think you’d need any qualification besides that, but be assured that I am sufficiently qualified :)
By the way, Wikipedia is not intrinsically less accurate than maths textbooks. Wikipedia has mistakes, sure, but I’ve found enough mistakes (and had them corrected for further editions) in textbooks. Your textbooks are correct, but you are misunderstanding them. As previously mentioned, the distributive law is about an algebraic substitution, not a notational convention. Whether you write it as
a(b+c) = ab + ac
or asa*(b+c) = a*b + a*c
is insubstantial.About the ambiguity: If I write
f^{-1}(x)
, without context, you have literally no way of knowing whether I am talking about a multiplicative or a functional inverse, which means that it is ambiguous. It’s correct notation in both cases, used since forever, but you need to explicitly disambiguate if you want to use it.I hope this helps you more than the stackexchange post?
That is incorrect. Multiplication does NOT have presedence of division, they are equal. So it’s left to right, which means division comes first.
Which brings you to a yet further ambiguous expression. I maintain that’s a poor choice.
#MathsIsNeverAmbiguous if you follow all the rules of Maths (there’s a lot of people here who aren’t).
2(4) is not exactly same as 2x4.
Correct! It’s exactly the same as (2x4).
No. No. You choose to be ignorant.
Ummm, I was agreeing with you??
Anyways, I’m a Maths teacher who has taught this topic many times - what would I know?
No, it’s 1, and only 1. Order of operations thread index
P.S. this is Year 7 Maths, not Year 1.