Poll: What is the answer to 48/2(9+3)?

[flippedthebitch]

I don't know why you want us to do your homework for you, but I got 288... after you do the parentheses, you're supposed to do them from left to right. I think it's a poorly written problem, though.

lol it's not a homework problem man, I'm not in middle school. This question is blowing up other forums and reddit.

48/2(12) = 2

Yeah, that's how I did it. But the way it's written, it doesn't specify if the only the 2 is being multiplied by 12 or if the entire fraction is. If the first, then it's 2. If the second, then it's 288.

So, as Professor Layton wisely pointed out, the problem is poorly written.

not really. due to the limitations of computers, we cant write fractions on forums quite as well as by hand, so one must assume that since the whole fraction was not in parenthesis to be multiplied, the multiplication by 12 only applies to the denominator of the fraction. and so, by adding (9+3) to get 12, then 12*2 to get 24, 48/24=2. simple

yay high school freshman pre calc class!

Hmmmmm. You should pay a little more attention in your calc class. If the intentionn was for the 9+3 to be applied only to the denominator then that would have to be expressed with parenthesis. When this isn't specified, then we do the operations of division and multiplication in order from left to right. So:

48/2(9+3) 48/(2(9+3))
48/2(12) 48/(2(12))
24(12) 48/24
288 2

When a multiplication and division step takes place in the same equation and the second operation isn't included in parenthesis to indicate that the question requires you to complete that operation first we have to read the question left to right. This is the way calculators would solve this problem. Of course if the question was written (48/2)*(9+3) it would remove all ambiquity.

Yay for 3rd year university mathematics

hmm, i see your point. i guess the first poster really is right in that the way the problem is written allows it to be easily taken either way, and so unless the writer had a specific way in mind, this is a debate that will never have a clear winner or right answer.
and which university? im just curious.

Ya it's silly the way its phrased, I'm sure specifically to get a reaction like this, but when the question doesnt specify with parenthesis which operation takes priority you have to read the question left to right. So the correct step is to divide the 48 by 2 before you multipy the 12 giving you 288. That would be how simple calculator solves this problem. Its funny cause you can program graphing calculators to preform operation using different rules and get different answers then people can use this to agrue points. But the correct algebraic system will never change. Why would it?

I am at the university of alberta in an education degree with a major in mathematics. I'm actually in the middle of a practicum teaching these mundane algebraic rules to grade 8 students. Its funny that almost every middle school students could do this problem with no issues but full grown adults struggle so much.

 

[Lunar Shadow]

Seems to be a bit of a culture break.
I think both parties are tight, it just depends on the way there instructors wrote stuff out. In my experience the 2(9+3) is in the denominator, as it is written without a multiplication sign which implies it is (2(9+3)). This is just badly written, as it should be clarified as the following: (48/2)(9+3), 48/(2(9+30)), or 48/2*(9+3)

2(9+3)=2*(9+3)

Notice the parts where I said "in my experience" and that it is dependent on the short hand your instructors used.

 

[mps4li3n]

Over here we used ":" for division, so in my mind the question is if who wrote it meant 48:2x(9+3)=288 or if it's 48:[2(9+3)]=2...

See how cultural differences can get in the way?

 

[ZephrC]

What's -4^2?

Look, math notation is stupid. Even mathematicians screw this shit up sometimes.

If I were in charge I'd make it so if things were ambiguous you had to have written it wrong, but I'm not in charge, so shit will continue to be unnecessarily confusing.

 

[Bearjing]

because there does not seem to be a function on most (if any) keyboards which allows for writing of fractions as we do on paper. so your approach makes as much sense as the other approach which gets 288.

To write a fraction on a computer you put both the numerator and denominator in their own parenthesis and a "/" in between them. For instance.

(a+b)/(c-d)

a+b is the numerator and c-d is the denominator.

 

[Keava]

All my life i was taught in school that division and multiplication are equal when it comes to order, so the whole thing would be 48:2 * (9+3) = 24 * 12 = 288.

Now as for logic following this:

48 divided by 2 is the same thing as 48 multiplied by 1/2 which removes the division.
You could write this problem as 48 * 1/2 * (9+3).

For answer to be 2 it would have to be written like this:

48/[2*(9+3)] - simple as that.

 

[Owyn_Merrilin]

I was taught that the / represented a fraction, and that there was ultimately no difference between fractions and division. Under those rules, if we were expected to see

48
----(9+3)
2

as opposed to

48
-----
2(9+3)

the problem would be written as

(48/2)(9+3)

However, the problem is written as 48/2(9+3), which makes it a fraction with 48 in the numerator, and 2(9+3) in the denominator. Any math people want to take a look at this interpretation?

Ok lets use PEMDAS (and yes you use left to right first when dealing with operators on the same level).

You first solve(simplify) what is in the parenthesis. So...
48/2(9+3)=48/2(12)

Now realize when something is in a parenthesis next to another number or variable or w/e, it means the same thing as x or *. so...
48/2*12

Since division and multiplication are on the same level you solve the first one on the left side then keep going right till it is finished. so..
48/2*12=24*12 then 24*12=288

Did you even read my post? I said that the way I was taught, the / always represents a fraction, because division is simply a way of manipulating fractions. As such, 48/2(9+3) would parse as

48
______
2(9+3)

instead of

48
----- (9+3)
2

What I'm saying is that I was taught to parse it as a completely different expression than you're parsing it as; the way I parse it, the answer is unequivocally 2, whereas you parse it as something that is absolutely 288. I wonder if we're seeing the result of regional dialects in the language of math...

 

[GundamSentinel]

2... still remember from grade school, Please Excuse My Dear Aunt Sally; Parentheses, Exponent, Multiply, Divide, Addition, Subtract. So... 9+3=12, 12*2=24, 48/24=2.

Going by the Dutch equivalent; Meneer Van Dale Wacht Op Antwoord (Mr. Van Dale waits for an answer), I come to the same conclusion: 2.

 

[Bearjing]

Seems to be a bit of a culture break.
I think both parties are tight, it just depends on the way there instructors wrote stuff out. In my experience the 2(9+3) is in the denominator, as it is written without a multiplication sign which implies it is (2(9+3)). This is just badly written, as it should be clarified as the following: (48/2)(9+3), 48/(2(9+30)), or 48/2*(9+3)

2(9+3)=2*(9+3)

Notice the parts where I said "in my experience" and that it is dependent on the short hand your instructors used.

All different short hand for the same problem will all equal the same answer. But leaving out the "( )" around the 2(9+3) isn't short hand it is a complete mistake. 48/2(9+3) is completely different than 48/(2(9+3))

 

[flippedthebitch]

i got 2

9+3*2=24
48/24

google changes the formula to look like this (48 / 2) * (9 + 3) = 288

google doesnt "change the formula". google uses proper order of operations. read the question left to right and preform the operations in order. Why are you multiplying the 2 by the 9+3 before you do the division? there is no reason to do this. The division step is done first. if the multiplication step was done first it would have to be included in brackets to indicate such. so it would look like 48/(2(9+3)).

 

[Sanglyon]

That's an old trolling question, but anyway:
IT engineer here, with also a degree in Applied Math.

Never heard of these "BEDMAS" or "PEMDAS", or whatever. We don't use that here. We just learn how to do it without mnemotechnic trick.
* and / have the same priority, as have + and -.
if there is no parenthesis, apply from left to right.

When written like this : 42/2(9+3),
it's equivalent to 42/2*(9+3).
also (42/2)*(9+3), but the first parenthesis are redundants.
42 divided by 2 multiplied by the sum of 9 and 3.
The result is 288.

To be 2, it should have been written 42/(2*(9+3)), where there are no redundant parenthesis.

The precedence of operators:

precedence _____operator ______(typical operation)
3 _____________ ^ _____________ exponentiation
3 _____________ - _____________ unary negation (right-associative)
2 _____________ * _____________ multiplication
2 _____________ / _____________ division
2 _____________ % _____________ remainder
1 _____________ + _____________ addition
1 _____________ - _____________ subtraction
-1_____________ ( _____________ begin-grouping
0 _____________ ) _____________ end-grouping (no precedence)

 

[edman270]

oh my god this is 11 pages long... the qestion is poorly phrased as any mathematician worth their salt will not use a "/" to indicate a fraction FOR EXACTLY THIS REASON. Rather they would write it as

48
--- X (9+3)
2

or they would out it as

48
---
2(9+3)

depending on what they meant

 

[Bearjing]

-snip

When writing it out on a computer / means "divide by." But that is what a fraction is anyways. 1/4 (one fourth) is just one dividing by 4 which equals .25.

 

[mps4li3n]

because there does not seem to be a function on most (if any) keyboards which allows for writing of fractions as we do on paper. so your approach makes as much sense as the other approach which gets 288.

To write a fraction on a computer you put both the numerator and denominator in their own parenthesis and a "/" in between them. For instance.

(a+b)/(c-d)

a+b is the numerator and c-d is the denominator.

Frankly situations like this where exactly why {} [] () exist in math, and i don't see why not to use them instead of doing left to right...

Now as for logic following this:

48 divided by 2 is the same thing as 48 multiplied by 1/2 which removes the division.
You could write this problem as 48 * 1/2 * (9+3).

No, still has a problem, because you can easily put it in (48*1)/[2 * (9+3)] on paper...

The problem is that "/" in writing is actually ____ and you can't easily tell what it encompasses... this is why this was never a math problem to begin with, but one of spelling/interpretation of signs.

Like i said, that's what [] {} where invented for...

 

[Kakujin]

The way it is put together, I'm going to have to go with 2 on this one, but it is kind of difficult to tell, without the help of proper placement, which was the intended order.

 

[flippedthebitch]

Seems to be a bit of a culture break.
I think both parties are tight, it just depends on the way there instructors wrote stuff out. In my experience the 2(9+3) is in the denominator, as it is written without a multiplication sign which implies it is (2(9+3)). This is just badly written, as it should be clarified as the following: (48/2)(9+3), 48/(2(9+30)), or 48/2*(9+3)

2(9+3)=2*(9+3)

Notice the parts where I said "in my experience" and that it is dependent on the short hand your instructors used.

All different short hand for the same problem will all equal the same answer. But leaving out the "( )" around the 2(9+3) isn't short hand it is a complete mistake. 48/2(9+3) is completely different than 48/(2(9+3))

THANK YOU! Good to see another sane mathematical person on the thread.

 

[Natasha_LB]

I got 288, but what has really amused me is how many variations of BODMAS there are:

1. BODMAS
2. BIDMAS
3. BEDMAS
3. PODMAS
4. PIDMAS
5. PEDMAS

I find it funny how we all have slightly different terms for it. Dose anyone know any more variations?

no i think that covers them all, and you wrote 3 twice, it should go to 6, not 3,3,4,5

Oops, now I look stupid : (
Bit of a hangover this morning so my brain's not working quite yet.

 

[The Shade]

It's 288.

48/2 is basically a fraction, which should automatically be simplified to 24/1 (also known as 24).

Then, once the parenthetical is completed (9+3=12)

You are left with 24x12.

Answer is 288.

 

[mps4li3n]

-snip

When writing it out and a computer / means "divide by." But that is what a fraction is anyways. 1/4 (one fourth) is just one dividing by 4 which equals .25.

The problem is that while doing operations (i have no clue if that's right in english) the parts after "/" could easily be part of the 4 there... like 1/4 and 1/(3+1)... except that in writing you wouldn't need the () because it's:
1
---
3+1

Which leads to confusion...

 

[Bearjing]

Frankly situations like this where exactly why {} [] () exist in math, and i don't see why not to use them instead of doing left to right...

IDK, i guess because it is just redundant once you know the rules and just makes things bigger.

i.e. why write out 1+(4*5) when 1+4*5 is the same thing.