48÷2(9+3) = ????

48÷2(9+3) = ????

  • 2

    Votes: 62 50.0%
  • 288

    Votes: 62 50.0%

  • Total voters
    124
Search This thread

newter55

Senior Member
Sep 14, 2010
2,273
178
Southern Michigan
This is amazing how deeply rooted we are in our belief that we are right.

Amazingly, anyone who has said that they are sure that their response is absolutely correct and the only viable outcome is proven wrong by the laws of math.

In order to obtain 288 we must ignore the distributive rule which states that we can distibute the 2 over the 9+3 and get the same result as if we first perform the addition within the parenthesis. Well, at this point we would surely all agree that if the problem ended there, without that nasty preceding symbol, this would be a short thread as both the pedmas wetters and the distibutive geeks would wind up at the same conclusion. However, the ambiguous introduction of division into the problem is where we seem to have such a great divide (pun intended) on what to do first. Ironically, the fault is not with the math, but the way the expression is written. Once again we can simplify a bit and see the the result clearly follows common rules including the one which, regardless of how hard you insist on pedmas, left to right, or any other mnemonic, it makes no difference whether you multiply first, then divide from right to left; followed by a bit of subtraction, add a bit, then subtract some more, as m/d are equal, and a/s are equal. So, to show this one in as simple of terms as possible we need only look at 1-1+1+1-1 or 3/1*2*3/2. Go ahead and get crazy by mixing them together, any way you cut it your answers will always be the same, we cannot with any logic argue a result other than that which is apparent.

Ok, so given that these rules are clear and easily understood, why the confusion?

Interpretation as a result of poor notation. Presumably we all understand that the we can replace the division with the inverse and multiply, but had the problem been written with this little operation excluded, we would not have a 20 page thread going as the result would once again be clear to all. Clarity seems to evaporate on how one would go about eliminating the division. Would the result be 48 * (1/2)(9+3), completely ignoring the implied distribution which we have shown is not the problem with the problem? or 48 * (1 / 2(9+3)) acknowledging the distribution and opening up the can of worms all over again? I presume one would be tempted to even go so far as write their inverse as (1 / (2(9+3))) so as to remove all doubt given the nature of this problem but that would end all the fun again.

It seems I have written enough to help muddy the waters for now but i hope that we can begin to see that if in fact the problem was expressed in a coherent manner, our methods used in obtaining our "incorrect" results are indeed valid whether we wind up with 2 or 288, the fault lies in the originator of this twisted little joke.
 
Last edited:

newter55

Senior Member
Sep 14, 2010
2,273
178
Southern Michigan
Haha newter

Miss your insights in the cap forums

Meh...just amazed at peoples conviction. There are many "tricks" in math but the underlying rules are not at fault. They are either done by violating a rule through deception or confusion. Clearly this one is simply written with the intention of ambiguity.
 
Last edited:

jamice4u

Senior Member
Problem proven through substitution.

1. 48
_____ = 2
2(x+3)

2. 48
_______ = 2
2x+6

3. 48(2x+6)
_______ = 2(2x+6) Cross multiply the 2x+6 on the left side.
(2x+6)

4. -12+48 = 4x + 12-12 Subtract 12 from both sides.

5. 36 = 4x divide 4 from both sides
__ __
4 4

6. x = 9

7. 48
______ = 2
2(9+3)
 
Last edited:

Vorbo

Member
Mar 21, 2011
7
0
What. The. F*ck. Is. That.

I've never seen "PEDMAS" before, I've always known it as BEDMAS.

Brackets -> Exponents -> Division/ Multiplication -> Addition/Subtraction

So you follow that order for operations. Division/ Multiplication and Addition/Subtraction are both first come first serve.

Following those rules the answer is 288.
 

jamice4u

Senior Member
I need to check my answers on excel.

The way I would read 48÷2(9+3) is as follows:

Forty-eight divided by two multiplied by the result of nine plus three.

In other words:

= 48 ÷ 2 (9 + 3)
= 48 ÷ 2 * 12
= 24 * 12
= 288
I mean, I may not be able to do logarithms and higher forms of math, but c'mon, if I can get order-of-operations correct, there's no excuse for anyone else. In order to get 2, you would have to write this as 48 ÷ (2(9+3)).
How come you did not divide 48 / (2*12) = 2 Enough said.
Why are people ignoring the division part in the problem? It is interesting that Wolfram-Alpha came up with 2 different answers because I add an extra set of parenthesis.
 
Last edited:

jamice4u

Senior Member
Unbiasis opinion to the problem. I guess it all depends where you are from.

This submission is currently being researched & evaluated!
You can help confirm this entry by contributing facts, media, and other evidence of notability and mutation.

Status:
Submission
Badges:
Featured, Researching
Year
2011
Origin
Unknown
Tags
math, troll, trick, 4chan, /b/, google

About
48÷2(9+3) = ? is a math problem that, depending on the order of operations used, leads to two different answers: 2 and 288. It can be a hot topic for debate, and is sometimes used to troll other users because of the argument that can result afterward.

Spread
This internet phenomenon exploded on April 7th, 2011, around the same time when searches for “48÷2(9+3) =” spiked on Google. The thread that first sparked interest in this problem was on Hot Pursuit, a small local forum based in Texas. Shortly afterwards a member of the site posted the query on BodyBuilding.com and was spread on wards. Other forum posts from that day include Physics Forums WallStreetOasis.com, SpartanTailgate, grasscity.com, Tennis Warehouse, Inside MD Sports, and The Escapist. On April 8th, it popped up on 6Theory, NIKETLK, Yahoo! Answers, DIYMA.com, and The Ill Community.

The Solution




Inputting the problem on different calculators can lead to different results depending on if the calculator is non-scientific or scientific, and how the calculator interprets order of operations.


There are considerable arguments for both answers, but the general consensus is that writing ambiguous fractions like “2/6x” makes solving such problems confusing, and it is considered bad form to write ambiguously written fractions in the first place.

Standard Order of Operations
If one strictly uses the standard order of operations to solve mathematical expressions, the answer to the problem would be 288, which is also the same solution provided by WolframAlpha and Google.

By convention, the order of precedence in a mathematical expression is as follows:

•Terms inside of Brackets or Parentheses.
•Exponents and Roots.
•Multiplication and Division.
•Addition and Subtraction.
If there are two or more operations with equal precedence (such as 10÷2÷5 or 7÷2*9), those operations should be done from left to right.

Therefore, the problem “48÷2(9+3) =” would be solved like this:

48 ÷ 2 * (9+3)=
48 ÷ 2 * (12)=
48 ÷ 2 * 12=
24 * 12=
288 PEMDAS
Solving for the answer 2 is sometimes a result of doing multiplication before division. Much of the confusion can be blamed on PEMDAS (sometimes known as, “Please Excuse My Dear Aunt Sally”) and other similar mnemonics used to teach order of operations in schools.

As an example, PEMDAS stands for:

•Parentheses
•Exponentiation
•Multiplication
•Division
•Addition
•Subtraction
Whereas BEDMAS stands for:

•Brackets
•Exponentiation
•Division
•Multiplication
•Addition
•Subtraction
The former can lead to the implication that addition always comes before subtraction, and that multiplication always comes before division. The latter can lead to the implication that addition always comes before subtraction, and that division always comes before multiplication.

If one uses multiplication before division (PEMDAS being especially popular in the United States), the problem would be solved like this:

48 ÷ 2 * (9+3)=
48 ÷ 2 * (12)=
48 ÷ 2 * 12=
48 ÷ 24=
2 However, solving the problem like this would be considered erroneous because multiplication and division hold equal precedence.


Some sources maintain that multiplication does not always comes before division:



- University of North Texas
- Northern Michigan University
- Deb Russell
- University of Minnesota Rochester
- Midland College
- Hofstra University



It is helpful to remember that division and multiplication are inverse operations, and thus represent the same operation written in a different way. Division is the same as multiplication of the reciprocal, and multiplication is the same as division of the reciprocal. This is similar to how addition is the same as subtraction of the negative, and how raising to the nth power is the same as taking the 1/nth root.

Implied Multiplication
However, the answer 2 could be justified by the principle of implied multiplication. For example, consider the problem "2/5x."

If one strictly follows the standard order of operations, the correct interpretation would be “(2/5)*(x).”

But many calculators and textbooks state that a higher value of precedence should be placed on implied multiplication than on explicit multiplication:

Because “5x” is implied to be "5*x," it gets higher priority than "2/5." In this case, "2/5x" would be interpreted as "(2)/(5*x)."

Returning to the original problem, if one utilizes the principles of implied multiplication, then “2(9+3)” gets higher precedence than the explicit “48/2,” and would be solved like this:

48 ÷ 2(9+3)=
48 ÷ 2(12)=
48 ÷ 24=
2
However, there is a lack of consensus on the value of implied multiplication.
 

Ayrlupine

Senior Member
Dec 31, 2009
83
7
You guys know that any self-respecting Mathematician wouldn't express a problem in such a terrible way, right?
Both answers are entirely feasible, because of the ambiguous way in which the equation is laid out.
That said, I went for 2, and I'm totally right because I'm just about to graduate with a degree in Maths. :p :D
 

GazaIan

Senior Member
Dec 27, 2010
1,570
404
Your basement
twitter.com
How come you did not divide 48 / (2*12) = 2 Enough said.

The problem is, you put parenthesis around the 2 and the 12. The only thing in Parenthesis should be the 12.

Because one number cannot be multiplied by itself (masturbation excluded) , you now work from left to right. The 2 is supposed to be outside of the parenthesis.

So you sir, have received an:

F.
 

Top Liked Posts

  • There are no posts matching your filters.
  • 2
    Pemdas anybody? Parantheses, exponents, mult, div, sub, addition? Am i wrong?

    Sent from my ADR6300 using XDA App

    This is correct, (Please Excuse My Dear Aunt Sally). The answer is 2. Anyone who disagrees needs to retake elementary school math :p

    Sent from my DROIDX using Tapatalk
    1
    For the slower people, iv'e inserted a pic below.. the answer is 2

    you can't divide 2(9+3) into 48, get it as a number first by using order of operations, then divide.
    1
    42?

    10chars
    1
    Let's ask a professor shall we?
    Here you go:
    This should end the war eh?
    1
    Im sorry but I am correct. Im upto the point in calculus where calculators dont even do us any good. The answer is 2. You get 2 different answers depending on the type of calculator. Scientific calculators say 2 and regular ones says 288 I believe.

    Sent from my......ummm...let me get back at'chya!

    False, my Casio fx-82ES answers the equation as 288
    5b900067-ddb0-cad2.jpg

    EDIT: For the answer to be 2 the equation should look like this
    5b900067-de33-1016.jpg

    Sent from my HTC Desire using XDA Premium App
Our Apps
Get our official app!
The best way to access XDA on your phone
Nav Gestures
Add swipe gestures to any Android
One Handed Mode
Eases uses one hand with your phone