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On April 08 2011 13:39 DarkPlasmaBall wrote:Except "48÷2(12) 48÷24=2" is an incorrect step. You do division (48÷2) to get 24 before you do the multiplication. PEMDAS. Multiplication and division are on the same tier, so you whichever one comes first from left to right. And then 24(12) is 288. I think it's embarrassing how over 40% of the people who took the poll got it wrong...
you continue to hold the (12) until the end. but the way you have done the problem you could have
reduced it initially to 24(9+3), and then 24(12) for 288. essentially your method ignores the parenthesis.
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Wow, some people here are so dumb it's not even funny. This is like basic mathematics...
48/2(3+9)
= 48 / 2 * (3+9) ........ 5(2) = 5*2, 4(1+1) = 4*(1+1), Note: the qn is not 48/(2(3+9)
= 48 / 2 * (12) ........ .. Further note: the qn is not 48
........................................................... -------------------
........................................................... 2 ( 3+9 )
= 12 * 48 / 2
= not 2
Note: 5*4*3 = 3*4*5, 2*3/4 = 3*2/4 = 2/4*3 etc etc as * and / can be switched around in an eqn without brackets.
eg. 9x8/7/6/5 = 1x9x8/7/6/5 = 1/5/6/7x8x9 = 9x1/7x8/6/5 etc etc
Note: 1/2 = _1_.......5x6/7/8 = _5_ x _6_ x _1_ x _1_
...................2.........................1........1...... 7.......8
I don't know about America, but to the rest of the world, this is how the / sign works.
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what more is there to discuss? it is like a dog trying to eat its own tail. even though it is written like an eight grade level problem, we can't forget PEMDAS, left to right, 288.
the poll in the OP is interesting because i think this is something that trips up the college educated people and is simple to even a HS dropout.
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I think that saying the answer of 288 is correct, but I can also see the merit in the answer being 2 since a lot of people might actually mean to include the parentheses even if they don't in the original problem. That maybe why different calculator versions might assume the parentheses since it might be the more common notation.
Saw this pic on another forum:
http://img339.imageshack.us/img339/9549/headasplode.jpg (Doesn't show up properly on image macro so click that link to see what is apparently a TI85 vs TI86 comparison)
Also, my scientific calculator spat out 2 as well. So it really is a matter of interpretation. Luckily math problems are never written in such a confusing manner, so I don't think it's a big deal either way.
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Yea, it's pretty sad how many people here are using this thread as a self-esteem boost, just because they got the right answer to a simple but misleading math question.
Tbh I did get 2 but at first glance i saw the question as:
48
-------- =?
2(9+3)
or
(48÷2)(9+3)=?
I'm a straight A math student and I can't say I wasn't surprised that I got the wrong answer. Still not sure if I'm actually wrong but idc since I stopped using the ÷ notation in grade 2 or 3.
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On April 08 2011 13:39 DarkPlasmaBall wrote:Except "48÷2(12) 48÷24=2" is an incorrect step. You do division (48÷2) to get 24 before you do the multiplication. PEMDAS. Multiplication and division are on the same tier, so you whichever one comes first from left to right. And then 24(12) is 288. I think it's embarrassing how over 40% of the people who took the poll got it wrong...
But this is not a law, just a notation. There is a bunch of different notations that do not use any of those rules, and it is easy to create notation where 48/2(2+2) = 6. You just define that implicit multiplication has bigger priority than division/explicit multiplication. This is actually used informally and there is no problem with that as long as people agree to interpret it like that. When you want to write something formally you just use parenthesis anyway.
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On April 08 2011 14:07 kuzyk wrote:Show nested quote +On April 08 2011 13:39 DarkPlasmaBall wrote:On April 08 2011 13:32 EEhantiming wrote:
i got 2
48÷2(9+3)
48÷2(12)
48÷24=2
Except "48÷2(12) 48÷24=2" is an incorrect step. You do division (48÷2) to get 24 before you do the multiplication. PEMDAS. Multiplication and division are on the same tier, so you whichever one comes first from left to right. And then 24(12) is 288. I think it's embarrassing how over 40% of the people who took the poll got it wrong... you continue to hold the (12) until the end. but the way you have done the problem you could have reduced it initially to 24(9+3), and then 24(12) for 288. essentially your method ignores the parenthesis.
I don't understand what you mean by that. EEhantiming already did the addition inside of the parentheses to get 12 on the inside first, and a number to the left of parentheses- like 24(12)- means multiplying that number times whatever value is inside the parentheses (or distributing if it's more than one term).
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On April 08 2011 14:15 WeeKeong wrote:
Wow, some people here are so dumb it's not even funny. This is like basic mathematics...
48/2(3+9)
= 48 / 2 * (3+9) 5(2) = 5*2, 4(1+1) = 4*(1+1), Note: the qn is not 48/(2(3+9)
= 48 / 2 * (12) Further note: the qn is not 48
-------------------
2 ( 3+9 )
= 12 * 48 / 2 Note: 5*4*3 = 3*4*5, 2*3/4 = 3*2/4 = 2/4*3 etc etc
= not 2 as * and / can be switched around in an eqn without brackets.
eg. 9x8/7/6/5 = 1x9x8/7/6/5 = 1/5/6/7x8x9 = 9x1/7x8/6/5 etc etc
Note: 1/2 = _1_ 5x6/7/8 = _5_ x _6_ x _1_ x _1_
2 , 1 1 7 8
I don't know about America, but to the rest of the world, this is how / works.
Does / indicate a fraction line or division sign? I'm just confused. According to the poll, 2/3 of poll takers read / as a fraction line, while I believe here that you use it as a division operator. Maybe everybody should just stop.. i know i will 
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apparently on BB.com, ppl have been e-mailing teachers and they're all saying the answer is 2. Whether they are lying or telling the truth, i dunno, maybe someone here should ask their teacher tomorrow.
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you're all wrong! the answer is 8 and two-thirds
have we all forgotten about the distributive factor?
it goes like this...
First, you have to distribute the 2 to both the 9 and 3, so it looks like this
48 / (2 x 9) + (2 x 3)
= 48 / 18 + 6
= 8.66666666666...
ㅋㅋㅋI love ambiguity. It leads to interpretation and second guessing.
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On April 08 2011 14:18 mcc wrote:Show nested quote +On April 08 2011 13:39 DarkPlasmaBall wrote:On April 08 2011 13:32 EEhantiming wrote:
i got 2
48÷2(9+3)
48÷2(12)
48÷24=2
Except "48÷2(12) 48÷24=2" is an incorrect step. You do division (48÷2) to get 24 before you do the multiplication. PEMDAS. Multiplication and division are on the same tier, so you whichever one comes first from left to right. And then 24(12) is 288. I think it's embarrassing how over 40% of the people who took the poll got it wrong... But this is not a law, just a notation. There is a bunch of different notations that do not use any of those rules, and it is easy to create notation where 48/2(2+2) = 6. You just define that implicit multiplication has bigger priority than division/explicit multiplication. This is actually used informally and there is no problem with that as long as people agree to interpret it like that. When you want to write something formally you just use parenthesis anyway.
Except 48/2(2+2) = 48/2(4) = 24/4 = 6 for the same mathematical laws (PEMDAS) explained previously, not because 48/2(2+2) = 48/2(4) = 48/8 = 6. That's purely coincidence, as was shown in the OP's problem. Your analogous example happens to have the same answer both ways, but math is certainly not up to interpretation of notation. Math is defined and instructed by universal laws.
You can't arbitrarily make multiplication have a bigger priority than division... that's not how math works. Unless you insert parentheses to depict priority, it's never assumed that the order of operations after the P in PEMDAS is violated. Ever. (At least, not in basic arithmetic o.O)
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On April 08 2011 14:24 pRo9aMeR wrote:
you're all wrong! the answer is 8 and two-thirds
have we all forgotten about the distributive factor?
it goes like this...
First, you have to distribute the 2 to both the 9 and 3, so it looks like this
48 / (2 x 9) + (2 x 3)
= 48 / 18 + 6
= 8.66666666666...
ㅋㅋㅋI love ambiguity. It leads to interpretation and second guessing.
You sir are my hero and win.
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On April 08 2011 14:24 pRo9aMeR wrote:
you're all wrong! the answer is 8 and two-thirds
have we all forgotten about the distributive factor?
it goes like this...
First, you have to distribute the 2 to both the 9 and 3, so it looks like this
48 / (2 x 9) + (2 x 3)
= 48 / 18 + 6
= 8.66666666666...
ㅋㅋㅋI love ambiguity. It leads to interpretation and second guessing.
From general consensus, the distributive property occurs between the 48 and the (9+3)
Also, in yours, distributive still always remains one term, so using your interpretation it would be 48/(2*9+2*3)=48/24=2
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United States10328 Posts
On April 08 2011 13:08 xxpack09 wrote:Show nested quote +On April 08 2011 12:58 Severedevil wrote:On April 08 2011 12:53 xxpack09 wrote:
PEMDAS/BEDMAS works from left to right. People tend to forget this.
Fourth-grade mnemonics do not reflect the usage of operators in any real mathematical context. You might as well tell me that five divided by two is equal to two remainder one. Except these "fourth-grade mnemonics" are correct in all situations.... They describe how to interpret symbols and operations in the correct manner. So no, that's a bad analogy. "Remainders" are informal whereas the order in which mathematical operations are carried out is as formal as it gets
Since we're just pointlessly continuing this thread, might as well keep it going.
"Remainder" is NOT an informal term. The concept of "k modulo n" is fundamental in number theory, and the generalized concept of quotients in algebra come with a "remainder": the quotient group G / H is precisely the group of "remainders" when we take all the elements of G and "mod out by" (or cancel) all the elements of H.
Anyway I should stop talking since I probably just said something wrong and need to study for my algebra test lol
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On April 08 2011 14:29 ]343[ wrote:Show nested quote +On April 08 2011 13:08 xxpack09 wrote:On April 08 2011 12:58 Severedevil wrote:On April 08 2011 12:53 xxpack09 wrote:
PEMDAS/BEDMAS works from left to right. People tend to forget this.
Fourth-grade mnemonics do not reflect the usage of operators in any real mathematical context. You might as well tell me that five divided by two is equal to two remainder one. Except these "fourth-grade mnemonics" are correct in all situations.... They describe how to interpret symbols and operations in the correct manner. So no, that's a bad analogy. "Remainders" are informal whereas the order in which mathematical operations are carried out is as formal as it gets Since we're just pointlessly continuing this thread, might as well keep it going. "Remainder" is NOT an informal term. The concept of "k modulo n" is fundamental in number theory, and the generalized concept of quotients in algebra come with a "remainder": the quotient group G / H is precisely the group of "remainders" when we take all the elements of G and "mod out by" (or cancel) all the elements of H. Anyway I should stop talking since I probably just said something wrong and need to study for my algebra test lol
What you said makes sense. Since it applies the most to computer science where % will the return the remainder when dividing integers. Remainders are a part of life if people like it or not. Mathematics has many different interpretations. The only issue is that with the one it uses a / sign which means division, which means we follow order of operation. Using a --- fraction sign gives an entirely different method and messes a lot of people up due to its large use in high school and later math when dealing with variables as opposed to strictly numbers.
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When people attempt to excuse their incorrect answers with "Math is open to interpretation", I'm out ^^ I certainly don't want to start getting angry
I suppose their math teachers should have done a better job at explaining the concepts 
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proof that answer = 2
If you have 48/2(9+3)
The 2 is attached to the (9+3), anyone who even got past algebra should remember factoring an equation out.
Example: 2(a+b)=2a+2b
2(9+3)=(18+6)
From there you get 48/(18+6)=48/24=2
not my work but i don't see how can this be wrong.
for proof, check out http://www.purplemath.com/modules/orderops2.htm 5th example.
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288
I'm pretty sure I learned order of operations in Elementary School
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oh sht, I thought I was all smart when i got 288. Then i read some posts and I am like damn. Thought I had it nailed after remembering to do the parenethesis first.
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EPT
