Solve 48

April 10, 2011

Typical 5th grade math, I guess no one is smarter than a 5th grader.

April 10, 2011

So what do you say to the evidence earlier that distributive multiplication does indeed have a higher order-of-operations presidence than other multiplication?

I say

(light heartedly, of course)

April 10, 2011

Typical 5th grade math, I guess no one is smarter than a 5th grader.

It is? I don't recall having a detailed discussion on the presidence of distributive multiplication versus standard multiplication in my 5th grade class. Also those who take the grade school PEMDAS a bit too literally can find themselves in trouble.

If I ever saw an equation written in the format of this one on an exam, I would ask the professor for clarification as to whether (9+3) were in the numerator or the denominator. Unless it was an intentional tricky question on a somewhat obscure presidence rule that seems pretty reasonable to me.

I also would not be surprised to see marks taken off of my work if I were to answer with an equation in this format, rather than in a much clearer fraction form.

April 10, 2011

48?2(9+3) = 288

48?[2(9+3)] = 2

:cool:

April 10, 2011

It is? I don't recall having a detailed discussion on the presidence of distributive multiplication versus standard multiplication in my 5th grade class. Also those who take the grade school PEMDAS a bit too literally can find themselves in trouble.

If I ever saw an equation written in the format of this one on an exam, I would ask the professor for clarification as to whether (9+3) were in the numerator or the denominator. Unless it was an intentional tricky question on a somewhat obscure presidence rule that seems pretty reasonable to me.

I also would not be surprised to see marks taken off of my work if I were to answer with an equation in this format, rather than in a much clearer fraction form.

I must admit, I'm not too familiar with the precedence of the distributive property in the order of operations, do you have any links to anywhere I can read about it?

By the way, what did you think the answer was?

April 10, 2011

I must admit, I'm not too familiar with the precedence of the distributive property in the order of operations, do you have any links to anywhere I can read about it?

By the way, what did you think the answer was?

LeeDogg's post on the second page: http://www.purplemath.com/modules/orderops2.htm (It's the 5th green equation).

At first I thought the answer was 288. By the order of operations I've been taught, the 2(9+3) becomes 2*12, and then you do multiplication and division in the same step from left to right. The other way to look at it is that 2(9+3) is a factoring of (18+6), and the rule about distributive presidence would confirm that.

My position though is still that the original equation is ambiguous.

48/[(2(9+3)] is a much better way to write it if you intend the answer to be 2.

48(9+3)/2 is a much better way to write it if you intend the answer to be 288.

April 10, 2011

Basically the answer depends on what rule you use. There is no universal way of calculating an equation that has not been configured using a universal format.

April 10, 2011

Basically the answer depends on what rule you use. There is no universal way of calculating an equation that has not been configured using a universal format.

Agreed 100%

It's first and foremost a formatting issue. There is more than one reasonable way to interpret that equation into a more standard format.

April 10, 2011

I'll assume the answer is in fact 288.

Based on that logic, then I will let X = (9+3).

In order for 288 to be the correct answer, the equation becomes 48/2*X = 24*X = 288.

Apply this to a generic algebraic example now, such as X/3X.

This is easily solvable as 1/3.

According to the above example, it would become X/3*X = X?/3.

I've never seen single line algebra done this way. It is excessively convoluted.

April 10, 2011

LeeDogg's post on the second page: http://www.purplemath.com/modules/orderops2.htm (It's the 5th green equation).

At first I thought the answer was 288. By the order of operations I've been taught, the 2(9+3) becomes 2*12, and then you do multiplication and division in the same step from left to right. The other way to look at it is that 2(9+3) is a factoring of (18+6), and the rule about distributive presidence would confirm that.

My position though is still that the original equation is ambiguous.

48/[(2(9+3)] is a much better way to write it if you intend the answer to be 2.

48(9+3)/2 is a much better way to write it if you intend the answer to be 288.

The distributive property precedence is the way I read it as well, so I would have come up with 2 as the answer with the formula as provided. It's been quite a while since I took math, but I really don't think this is as ambiguous as some have stated here as the distributive rules clearly apply.

April 10, 2011

My answer would be 2.

Not because multiplication takes precedence over division.

My reason is summarized here >

Therefore,

48?2(9+3) = 2

48?2*(9+3) = 288

This is because I understand an algebraic statement 2x to be equal to 2(x), and this takes priority over regular multiplication and division. Therefore, 9?2x is equivalent to 9?2(x) which gives me 4.5 / x, instead of 4.5(x).

To further support the 2 answer, I think a key factor here is that the distributive law of multiplication does NOT work for division

The Distributive Law does not work for division:
Example:

24 / (4 + 8) = 24 / 12 = 2, but

24 / 4 + 24 / 8 = 6 + 3 = 9

http://www.mathsisfun.com/associative-commutative-distributive.html

So therefore per the distributive law of multiplication only the 2 can be distributed and since Parenthesis come first, the expression (2x9 + 2x3) needs to be calculated FIRST, before it can be divided into 48.

Using the wording from that site, I believe this expression would read as 48 divided by the sum of 2 lots of 9 plus 2 lots of 3.

April 10, 2011

The distributive property precedence is the way I read it as well, so I would have come up with 2 as the answer with the formula as provided. It's been quite a while since I took math, but I really don't think this is as ambiguous as some have stated here as the distributive rules clearly apply.

Yeah this is what I think now. Although, 20 minutes ago I didn't

I've been reading up on multiplication by juxtaposition which apparently should take precedence over any other multiplication or division

If that's the case then 2(9+3) should be evaluated first.

If I put the equation as it's written into my calculator (Ti-89) then I get 288. However, if I substitute the 9+3 for x and the 2 for y and input 48/y(x) then it uses this juxtaposition rule and gives me $gif.latex?\frac{48}{y(x)}$

If you substitute the numbers back in then you get $png.latex?\frac{48}{2(9+3)}%20=%202$

So I'm still not sure, but I'm swaying towards 2.

April 10, 2011

#include &lt;iostream&gt;
using namespace std;

int main()
{
cout &lt;&lt; 48 / 2 * (9+3);

return 0;
}

lulz.

I'm thinking 2, but I'm now letting facebook decide.

April 10, 2011

Solve 48?2(9+3)

post answers and why :p

BODMAS

Brackets

Order (^ / to the power of)

Division

Multiplication

Addition

Subtraction

Therefore:

(9+3) = 12

48 ? 2 = 24

12*24 = 288

April 10, 2011

288, without a doubt

April 10, 2011

Typing this into C++ or C# or python etc is useless because you are inserting a * in so the 'juxtaposition rule' won't take effect. Adding a multiplication symbol changes the equation.

April 10, 2011

Typing this into C++ or C# or python etc is useless because you are inserting a * in so the 'juxtaposition rule' won't take effect. Adding a multiplication symbol changes the equation.

Exactly.

April 10, 2011

(48 ? 2) * (9 + 3) = 288

Because Google says so. :laugh:

April 10, 2011

what field are you working in?

April 10, 2011

do people not friggin read?

The expression is 2(9+3)

not (9+3)

So parentheses first is (2 x 9 + 2 x 3) divided into 48

April 10, 2011

do people not friggin read?

The expression is 2(9+3)

not (9+3)

So parentheses first is (2 x 9 + 2 x 3) divided into 48

:)

April 10, 2011

BODMAS?

9+3=12

2*12=24

48?24=2

So 2? :unsure:

I've soo got this all wrong, right?

April 10, 2011

Surely the 4chan threaded ended in blood after this.. haha

April 10, 2011

April 10, 2011

do people not friggin read?

The expression is 2(9+3)

not (9+3)

So parentheses first is (2 x 9 + 2 x 3) divided into 48

Brackets first :p I can't believe this thread is still going on, especially after the first reply got it right.

Let's see what we have:

48:2*(9+3)

We do brackets first

48:2*(12)

no need for brackets anymore

48:2*12

once each of the operations are of the same level (and multiplication and division are the same level operations), you just do it left to right

48:2*12 = 24*12 = 288

/thread

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