What is 2+3×4?
- Thread starter Howie
- Start date
Pink Cadillac
Giga Poster
14 because you do multiplication before addition. I love my 4 times tables.
Pink Cadillac
Giga Poster
BIDMAS was designed to help eliminate confusion like this and tells you which sums you do in what order.
Brackets
Indices (which is like the power of something)
Division
Multiplication
Addition
Subtraction
As multiplication is higher on the list than addition you times it first before adding.
Brackets
Indices (which is like the power of something)
Division
Multiplication
Addition
Subtraction
As multiplication is higher on the list than addition you times it first before adding.
Howie
Donkey in a hat
Ah ha - there's the key word; rules.
The rule you're referring to is the order of operations, right? Multiplication/division before addition/subtraction? So you multiply the 3 by the 4 before adding the 2, yes?
My problem is this; the order of operations is a 'rule' that was made up by mathemeticians about 400 years ago, to help standardise equations such as this, right?
But just because something is a rule, does that make it fact? Does it make it truth?
Does that mean that 2 plus 3 times 4 is 14?
I'm not so sure it does.
I realise at this point that this now becomes a philosophical question rather than a mathematical one - and I'm not saying anyone is right or wrong - I'm just curious as to how many people are aware of the order of operations and who uses it.
The rule you're referring to is the order of operations, right? Multiplication/division before addition/subtraction? So you multiply the 3 by the 4 before adding the 2, yes?
My problem is this; the order of operations is a 'rule' that was made up by mathemeticians about 400 years ago, to help standardise equations such as this, right?
But just because something is a rule, does that make it fact? Does it make it truth?
Does that mean that 2 plus 3 times 4 is 14?
I'm not so sure it does.
I realise at this point that this now becomes a philosophical question rather than a mathematical one - and I'm not saying anyone is right or wrong - I'm just curious as to how many people are aware of the order of operations and who uses it.
JoshC.
Strata Poster
The trouble with these sorts of expressions is that they are slightly ambiguous.
Mathematically speaking, the expression is poorly written (and I'd argue that it's out right incorrect). There should be some form of brackets; either (2+3)x4 or 2+(3x4). So these sorts of problems never - should! - arise in maths. However, the boring explanation is essentially that since the integers form a ring, you can only ever take 2+3x4 to mean (2+3)x4 when the brackets are explicitly there. So when they are not there, you have to assume it means 2+(3x4).
The thing is, maths is just a set of rules - these rules define what is fact and truth. Maths, equations, expressions, all exist outside the "real" world. So there's no way to determine if something is a fact in the same way would in the real world. For example, we can know whether or not "I am sitting at my desk typing this post at 9:47pm on 16/4/16" is a a fact or not. We can't really do this in the same way with maths. So, the set of rules which are "made up" do define the truths of maths; but of course, there are plenty of nitty gritty things behind those rules as to why they must be the way they are.
So, in theory, everyone should be aware of the order of operations and should use it, since that is the "right" way to do it!
Of course, everything I've said is just my opinion on all this / my understanding of things. But the points you're raising here are quite heavy. I studied maths at uni so got to understand a lot of the nitty gritty things behind why the rules are the way they are, but also did some philosophy stuff to see the viewpoints of how we get to 'mathematical truths' and the like.
Mathematically speaking, the expression is poorly written (and I'd argue that it's out right incorrect). There should be some form of brackets; either (2+3)x4 or 2+(3x4). So these sorts of problems never - should! - arise in maths. However, the boring explanation is essentially that since the integers form a ring, you can only ever take 2+3x4 to mean (2+3)x4 when the brackets are explicitly there. So when they are not there, you have to assume it means 2+(3x4).
Howie said:
The thing is, maths is just a set of rules - these rules define what is fact and truth. Maths, equations, expressions, all exist outside the "real" world. So there's no way to determine if something is a fact in the same way would in the real world. For example, we can know whether or not "I am sitting at my desk typing this post at 9:47pm on 16/4/16" is a a fact or not. We can't really do this in the same way with maths. So, the set of rules which are "made up" do define the truths of maths; but of course, there are plenty of nitty gritty things behind those rules as to why they must be the way they are.
So, in theory, everyone should be aware of the order of operations and should use it, since that is the "right" way to do it!
Of course, everything I've said is just my opinion on all this / my understanding of things. But the points you're raising here are quite heavy. I studied maths at uni so got to understand a lot of the nitty gritty things behind why the rules are the way they are, but also did some philosophy stuff to see the viewpoints of how we get to 'mathematical truths' and the like.
Howie
Donkey in a hat
^Very interesting.
You get these sort of things cropping up on Facebook sometimes - you've seen them; "Only 2% of people will get this right" - and they've usually got like half a million comments on them and no 2 people give the same answer. Well those things annoy me, so to get the definitive answer to this thorny mathematical conundrum I thought I'd put it to the only people who'd know for sure: a bunch of forum-dwelling coaster freaks!
You get these sort of things cropping up on Facebook sometimes - you've seen them; "Only 2% of people will get this right" - and they've usually got like half a million comments on them and no 2 people give the same answer. Well those things annoy me, so to get the definitive answer to this thorny mathematical conundrum I thought I'd put it to the only people who'd know for sure: a bunch of forum-dwelling coaster freaks!
LiveForTheLaunch
CF Legend
I don't care too much about the philosophical "just because it's a rule doesn't make it true," because you can say that about literally anything in life. However, I was taught BEDMAS, thus the answer is 14.
jayjay
Giga Poster
It's perfectly valid, and I'd write it like that if it were to be read by other mathematicians/scientists because we're lazy and like to write as little as possible (algebra usually just drops the x altogether).
In the end, maths is a language. All that matters is that your audience knows what you're trying to say. BODMAS is a convenient way to make sure everyone's on the same page. Questions like this on Facebook generally annoy me because it turns into an exercise in pedantry.
What is 2+3x4? Poor syntax.
It's the same problem as "Hang him not wait for me to arrive" or "tim helped his uncle jack off the horse". Ambiguity arises because the syntax - the language rules - are not followed.
As such, question such as these are not math problems, they're syntax problems. According to the well-defined syntax of maths, 2+3x4 ought to be written (2+3) x 4 or 2 + (3x4) to avoid confusion, and in cases of doubt, you are supposed to assume the latter. I never learned the English mnemonics for the order of operations, but examples aplenty have already been posted in the thread, and they all say the same: Do the multiplication before the addition.
Also, if you ever come across such intentionally poorly worded questions on Facebook, do yourself a favour and unfollow the page/unfriend whoever commented. They are set up to create pointless discussion between idiots who never learned the syntax, in order to generate as much traffic as possible. Sites sinking to those clickbaity lows do not deserve your attention or your wall space.
It's the same problem as "Hang him not wait for me to arrive" or "tim helped his uncle jack off the horse". Ambiguity arises because the syntax - the language rules - are not followed.
As such, question such as these are not math problems, they're syntax problems. According to the well-defined syntax of maths, 2+3x4 ought to be written (2+3) x 4 or 2 + (3x4) to avoid confusion, and in cases of doubt, you are supposed to assume the latter. I never learned the English mnemonics for the order of operations, but examples aplenty have already been posted in the thread, and they all say the same: Do the multiplication before the addition.
Also, if you ever come across such intentionally poorly worded questions on Facebook, do yourself a favour and unfollow the page/unfriend whoever commented. They are set up to create pointless discussion between idiots who never learned the syntax, in order to generate as much traffic as possible. Sites sinking to those clickbaity lows do not deserve your attention or your wall space.
Jordanovichy
Credit Whore 2016
It really pisses me off that basic 17p calculators from tesco can't do BIDMAD or BODMAS or whatever you want to call it.
But yeah, 14.
But yeah, 14.
Bat Fastard
Hyper Poster
14. Order of operations, PEMDAS.
PeskyTrimBrake
Hyper Poster
PEMDAS
Parenthesis
Exponents
Multiplication
Division
Addition
Subtraction
3x4=12+2=14
Who the hell is that one person who voted for 20?
Parenthesis
Exponents
Multiplication
Division
Addition
Subtraction
3x4=12+2=14
Who the hell is that one person who voted for 20?