48÷2(9+3) = ?

[javacontour]

Originally Posted By: rpn453
I went with 2 because, since I would never use a division sign in a calculation because of its inefficiency in conveying information, I simply saw it as a big forward slash, putting the rest of the numbers below it.

To really know the answer, you'd have to ask the writer about the intent and meaning of his poorly written mathematical expression.


A shorter version of what I just wrote.

 

[Al]

O.K....I'll flip flop too. If it had the "÷" it should also have had the "x". Poorly written.

I'm out.

 

[oldmaninsc]

Originally Posted By: CivicFan

Fortunately, Microsoft doesn't hire illiterates to design their software. Excel formula =48/2*(9+3) gives the right answer 288


Illiterates? Maybe not. But great software writers?

Anyone remember Windows 95, 98 and Me - just to name a few?

 

[JHZR2]

Originally Posted By: d00df00d
It's not a matter of whether you can or can't do math. It's a matter of how you see what is presented.

If the problem were written as 48 ÷ 2 * (9 + 3), it'd be easier to see: divide 48 by 2, and then multiply the result by the sum of 9 and 3. But the way it's written, some people see it as a fraction with 48 on top and 2(9 + 3) on the bottom, which leads to a different answer.

It's quite simple!


That's right. The way it is written, without the multiplication sign between the 2 and ( would indicate it as a fraction like:

48 / 2(9+3)

If we used letters instead:

48/ 2(y+z)

Id look at it as 48/ (2y + 2z). This would turn into 48 / (18+6) = 48 /24 = 2.

Alas, it is serial. The parenthesis throw people off, but in this case the order is inconsequential in reality.

48/2 * (9+3) = 216 + 72 = 288

 

[Quattro Pete]

Originally Posted By: Drew99GT
Here is the correct answer. The original equation is written incorrectly. It's either one depending on how you interpret it. Using correct algebra expressions, it can be either one. I hope this doesn't interrupt the space time continuum...

Wrong!

There is nothing left to the interpretation. 48÷2(9+3) and 48÷(2(9+3)) are two different things.

Your first expression depicts 48÷(2(9+3)).
Your second expression depicts 48÷2(9+3).

It's that simple.

 

[Nick R]

I ran it by both my parents, had them both do it. Both also came up with the answer of 2. My mom has a masters in business accounting, and my dad has to do physics pretty much on a daily basis, but without a degree.

They say that they were tought that the division symbol MEANS a / .

In other words

48/
2(9+3)

 

[Quattro Pete]

Originally Posted By: Nick R

They say that they were tought that the division symbol MEANS a / .

Well, it does, but it does not apply to everything after this symbol, unless everything after this symbol is in parenthesis. If it is not, then the / symbol applies only to the number directly behind it.

To be fair, I also struggled with it initially, even though I was pretty good at math in school, but that was some 20 years ago. If you don't use it, you lose it.

 

[Nick R]

Originally Posted By: Quattro Pete
Originally Posted By: Drew99GT
Here is the correct answer. The original equation is written incorrectly. It's either one depending on how you interpret it. Using correct algebra expressions, it can be either one. I hope this doesn't interrupt the space time continuum...

Wrong!

There is nothing left to the interpretation. 48÷2(9+3) and 48÷(2(9+3)) are two different things.

Your first expression depicts 48÷(2(9+3)).
Your second expression depicts 48÷2(9+3).

It's that simple.


We were always tought to multiply numbers that are directly multiplying parenthesis first. So in that case, it's 2. Math can be ambiguous, in certain circumstances, depending on the equation.

 

[Quattro Pete]

Originally Posted By: Nick R
We were always tought to multiply numbers that are directly multiplying parenthesis first. So in that case, it's 2.

Blame it on your teachers.

48÷2(9+3) is basically the same as
48÷2x12

not 48÷(2x12)

 

[CharlieJ]

My TI-84 and TI-89 Titanium calculators say 288. The calculator on Linux says "Malformed Expression".

 

[OVERKILL]

Originally Posted By: OVERK1LL
My sister is doing her PhD defense in a couple months... for math. I'm going to ask her how she sees it.

-Chris



Her response:

Quote:
Chris, I would say 48/2(12) is really the same as 48/2*12 (although ambiguous). And since you do BEDMAS left to right, you would get 288.
For example, if you had 4/1*3 , you have both multiplication and division. But since they have equal weight, you use the left to right rule and get 12, and not 1.3333 (repeat)

I think the original ambiguity was the bracket - do you eliminate them first? That is the subtle question here. There isn't really a "rule" for that.


She's a heck of a lot more qualified to speak on this subject than I am.

 

[kender]

Originally Posted By: Quattro Pete
Originally Posted By: Nick R

They say that they were tought that the division symbol MEANS a / .

Well, it does, but it does not apply to everything after this symbol, unless everything after this symbol is in parenthesis. If it is not, then the / symbol applies only to the number directly behind it.

To be fair, I also struggled with it initially, even though I was pretty good at math in school, but that was some 20 years ago. If you don't use it, you lose it.



I had Algebra 35 years ago. No calculators. We used the division symbol that this equation uses. The way that this equation is written we would add the numbers inside the "()"first. Then multiply the sum by the number to the left of the "(" because there is no "x" between the 2 and the "(". If there was a "x" between the 2 and the "(" you would solve the equation differently. Then the answer would be 288. As it is written the answer is 2.

go to MyAlgebra.com . Type in the equation exactly as it is written. 2

 

[Vikas]

If X=10, how much is 1/2X ?

Is it 0.05 or is 50.0 ??

This is the simplest example that I came up with.

On similar topic, can somebody show me how 1/(4+5) = 1/4 + 1/5 using distributive properties? You see, they never taught PEMDAS acronym in my country

I like this topic but I am sure there will be somebody who will manage to get this locked.

- Vikas

 

[kender]

0.05

Or maybe not. I don't know if the "/" is used the same way as the traditional division symbol. With the traditional symbol the answer is 0.05

 

[Quattro Pete]

Originally Posted By: Vikas
On similar topic, can somebody show me how 1/(4+5) = 1/4 + 1/5 using distributive properties?

But 1/(4+5) does not equal 1/4 + 1/5.

1/(4+5) = 1/9 = 0.11111
1/4 + 1/5 = 0.25 + 0.2 = 0.45

 

[mechanicx]

Originally Posted By: OVERK1LL
My sister's reply:

Quote:

Chris, I would say 48/2(12) is really the same as 48/2*12 (although ambiguous). And since you do BEDMAS left to right, you would get 288.
For example, if you had 4/1*3 , you have both multiplication and division. But since they have equal weight, you use the left to right rule and get 12, and not 1.3333 (repeat)

I think the original ambiguity was the bracket - do you eliminate them first? That is the subtle question here. There isn't really a "rule" for that.


Well I'm on page 5 so far and I agree with you and I guess your sister that it is 288. The people who are arguing 48 becomes the numerator and the answer is 2 are also saying the following: 48/[2(9+3)]=48/(2*12) etc, but that is not how the original problem is written. I could be wrong since it ahs been a while since I've had math courses and I haven't looked up the order of operations, but this is how I remember it.

 

[Quattro Pete]

Originally Posted By: kender
The way that this equation is written we would add the numbers inside the "()"first. Then multiply the sum by the number to the left of the "(" because there is no "x" between the 2 and the "(".

Why are you doing multiplication before doing division? Multiplication does not have precedence over division. They both have equal weight, which means that you go from left to right. Since division is the first on the left, you do it first.

Quote:

If there was a "x" between the 2 and the "(" you would solve the equation differently. Then the answer would be 288. As it is written the answer is 2.

Weird. Whether there's an "x" or no "x", it means exactly the same thing from a math perspective, so you should not be solving it differently.

Quote:

go to MyAlgebra.com . Type in the equation exactly as it is written. 2

MyAlgebra.com is wrong. I feel sorry for kids who try to learn from it.

 

[kender]

Originally Posted By: Quattro Pete
Originally Posted By: kender
The way that this equation is written we would add the numbers inside the "()"first. Then multiply the sum by the number to the left of the "(" because there is no "x" between the 2 and the "(".

Why are you doing multiplication before doing division? Multiplication does not have precedence over division. They both have equal weight, which means that you go from left to right. Since division is the first on the left, you do it first.

Quote:

If there was a "x" between the 2 and the "(" you would solve the equation differently. Then the answer would be 288. As it is written the answer is 2.

Weird. Whether there's an "x" or no "x", it means exactly the same thing from a math perspective, so you should not be solving it differently.

Quote:

go to MyAlgebra.com . Type in the equation exactly as it is written. 2

MyAlgebra.com is wrong. I feel sorry for kids who try to learn from it.


So MyAlgebra.com is wrong huh? I guess all the math teachers I had back in the 70's were wrong too. LOL!!

 

[Quattro Pete]

Originally Posted By: kender

So MyAlgebra.com is wrong huh? I guess all the math teachers I had back in the 70's were wrong too. LOL!!

Yup.

I've had a few clueless math teachers over the years, too, sadly.

 

[Johnny]

Well, I've come to one conclusion, six pages of disagreement means all of you would qualify to be congressmen and run the budget.