the math apocalypse: 48÷2(9+3) = ?

[#Ravencroft]

http://math.berkeley.edu/~gbergman/misc/numbers/ord_ops.html

Im officially stumped. My old calc II professors says 288, my uncle who's an engineer says 288 and you're saying 2 according to a generally reliable website. I guess it is ambiguous

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[Blockzillahead]

ill ask my calc prof monday

[Ipquarx]

Im officially stumped. My old calc II professors says 288, my uncle who's an engineer says 288 and you're saying 2 according to a generally reliable website.

Fun fact: That article says nothing about how the equation should actually be answered. So essentially he's saying "in my opinion, it's 2, but this website says that it can be either because forget teachers"

[otto-san]

the division symbol is the dumbest thing ever and nobody past fifth grade should ever use it ever

any operator deals with the two surrounding values, however they need to be evaluated
the problem is flawed i call high shenanigsnsd

is it

48(9 + 3)
_______
2

or is it

48
____
2(9+3)

that is the real question here

anyone past fifth grade would probably tell you without hesitation it's the former if you write it out like someone that's not still learning what a snake is

[Blockzillahead]

the division symbol is the dumbest thing ever and nobody past fifth grade should ever use it ever

any operator deals with the two surrounding values, however they need to be evaluated
the problem is flawed i call high shenanigsnsd

is it

48(9 + 3)
_______
2

or is it

48
____
2(9+3)

that is the real question here

with what i have been taught and seen other people do i believe it is written as;
48(9 + 3)
_______
2

i just cant see it as the other way around

[otto-san]

for it to be written
48
____
2(9+3)

the problem would have to be

48 / 2 / (9+3)

which is completely different. grouping the 2 with the parenthesis doesn't make it associate differently, it's just a way to remove the operator and make the math more readable

[#Ravencroft]

My professor in my current calc course goes off topic for like 30 minutes whenever someone asks a question on a tough problem. I'm gonna ask what the answer to this equation is and see how long the debate goes on lol.

[$trinick]

I'll ask a calc professor at my university too.

[Blockzillahead]

that happens in my calc class too lol
one minute were talking about math the next its some sort of life lesson or experience from the prof

[Doomonkey]

http://math.berkeley.edu/~gbergman/misc/numbers/ord_ops.html

That professor is just wrong though. The professor makes the claim that there is no convention, therefore the question is ambiguous. The professor states that there is likely no convention because one does not often get long linear multiplication-division problems.

The fact that every single calculator that knows order of operations will solve the problem as 288 indicates that there is, indeed, a convention.

[$trinick]

Incidentally, it is worth noting that in certain cases, no convention is needed.  The meaning of  a+b+c  is unambiguous even without the "left-to-right" convention, by the associativity of addition, and similarly  abc  by associativity of multiplication.  By further properties of the operations, the values of  a+b−c  and  ab/c  come out the same whichever order one uses.  In contrast,  a−b+c  and  a−b−c  require the "left-to-right" rule, while in the absence of a corresponding rule for multiplication and division,  a/bc  (as discussed above), and likewise  a/b/c,  are ambiguous.

[Doomonkey]

Yeah. I'm saying that there is a left-to-right rule for multiplication and division. He claims that there isn't.

[BluetoothBoy]

I find it easier in some situations to just think of division as multiplication for the reciprocal, and subtraction as addition of negative numbers. Not necessarily completely relevant to this problem, but it can help when confused about the OoO.

So I get the whole ambiguity thing, but I was always taught that when you have something like 2(9+3), you either distribute first or treat it as a single term. However, this obviously produces issues in some cases. So the real issue is not that anyone here is "doing it incorrectly" but rather that PEMDAS needs to be ammended.

[dkamm65]

http://www.wolframalpha.com/input/?i=48%C3%B72%289%2B3%29

Parenthesis.
Factorials.
Exponents.
Multiplication and division, left to right.
Addition and subtraction, left to right.

It's 288.

[Georges]

I find it amazing that there are over 220 replies and 15 pages of people arguing over one math problem.