6÷2(1+2)=?

Chemistry Ftw

Type it on a calculator the exact way it is presented, calculators always multiply before division... so I would go with that :P

seamus

28064212 wrote: »

Changing it to the same operator doesn't really clear it up. Is it 6 * ½ * (2 + 1) or should it be 6 * 1/(2 * (2 + 1))? You don't know whether you should get the reciprocal of 2 or the reciprocal of 2 * (2 + 1)

Of course you do. As said, you work from the left. In your second example there, you've added a parentheses to the equation, which fundamentally changes it. I didn't add or remove anything from the equation, it remains unchanged.

EL_Loco

if you use it like a fraction it makes it a bit easier (in my mind anyway)

something like

6/2(2+1)

3(3)

9

I'll jump out here, I'm off to hand back my degree. :S

28064212

Chemistry Ftw wrote: »

Type it on a calculator the exact way it is presented, calculators always multiply before division... so I would go with that :P

They really don't. And if yours does, you should replace it with one that follows the rules of mathematics.
6 ÷ 2 * 3 = 9
6 * 2 ÷ 3 = 4

seamus wrote: »

Of course you do. As said, you work from the left. In your second example there, you've added a parentheses to the equation, which fundamentally changes it. I didn't add or remove anything from the equation, it remains unchanged.

6 ÷ 2 * 3 (I'm replacing 1+2 with 3 for clarity's sake)

Without using the associativity rules, you don't know whether the division is 6 ÷ 2 or 6 ÷ (2 * 3). You can't get the reciprocal until you know what the divisor is. You've just selected 2 by working from the left, which already clears it up: (6 ÷ 2) * 3. Converting it to the same operator doesn't give any more clarity

Screaminmidget

Lookit, do the brackets first:
6/ 2x1 + 2x2
2 + 4
6
Therefore. 6/6 = 1
QED

Chemistry Ftw

28064212 wrote: »

They really don't. And if yours does, you should replace it with one that follows the rules of mathematics.
6 ÷ 2 * 3 = 9
6 * 2 ÷ 3 = 4


6 ÷ 2 * 3 (I'm replacing 1+2 with 3 for clarity's sake)

Without using the associativity rules, you don't know whether the division is 6 ÷ 2 or 6 ÷ (2 * 3). You can't get the reciprocal until you know what the divisor is. You've just selected 2 by working from the left, which already clears it up: (6 ÷ 2) * 3. Converting it to the same operator doesn't give any more clarity

Your changing it now... if you type 6÷2(1+2) you will get one! try it. If you type 6÷2x3 you will get 9.

nickcave

It my work (MSc Applied Maths) I never use the ÷ symbol, nor do i find that anybody does. We also never use BOMDAS or BODMAS or any rule like that.

That said, we all know that the reason there's confusion over whether multiplication come before division or vice versa is that division by a term is simply multiplication by it's inverse. This is always the way division is dealt with in professional maths.

So,

6 ÷ 2(1 + 2) =

6 x 2(1 + 2)^-1 =

6^-1 x 2(1 + 2) =

(1/6) x 2 x (1 + 2)

And what is the answer now? Since multiplication is associative, it doesn't matter what the order is.






(Hint: It's 1)

Chemistry Ftw

nickcave wrote: »

It my work (MSc Applied Maths) I never use the ÷ symbol, nor do i find that anybody does. We also never use BOMDAS or BODMAS or any rule like that.

That said, we all know that the reason there's confusion over whether multiplication come before division or vice versa is that division by a term is simply multiplication by it's inverse. This is always the way division is dealt with in professional maths.

So,

6 ÷ 2(1 + 2) =

6 x 2(1 + 2)^-1 =

6^-1 x 2(1 + 2) =

(1/6) x 2 x (1 + 2)

And what is the answer now? Since multiplication is commutative, it doesn't matter what the order is.






(Hint: It's 1)

What he said...

28064212

Chemistry Ftw wrote: »

Your changing it now... if you type 6÷2(1+2) you will get one! try it. If you type 6÷2x3 you will get 9.

The google calculator already supplied above disagrees with you

nickcave wrote: »

It my work (MSc Applied Maths) I never use the ÷ symbol, nor do i find that anybody does. We also never use BOMDAS or BODMAS or any rule like that.

That said, we all know that the reason there's confusion over whether multiplication come before division or vice versa is that division by a term is simply multiplication by it's inverse. This is always the way division is dealt with in professional maths.

So,

6 ÷ 2(1 + 2) =

6 x 2(1 + 2)^-1 =

6^-1 x 2(1 + 2) =

(1/6) x 2 x (1 + 2)

And what is the answer now? Since multiplication is commutative, it doesn't matter what the order is.[/SIZE]

Oh-oh, argument from authority. Why are you grouping 2(1+2) together to get the inverse? Do you agree that 2(1+2) is shorthand for 2 * (1+2) and they are exactly equivalent?

HeisenbergBB

It's 27.4

Can't believe this is even debatable

JustAddWater

It's pi

Mmmmmm pie ...

Screaminmidget

Chemistry Ftw wrote: »

Your changing it now... if you type 6÷2(1+2) you will get one! try it. If you type 6÷2x3 you will get 9.

they're different equations altogether...

seamus

Deleted User wrote: »

Can't believe this is even debatable

You come up against some curiosities borne out of incorrect, incompetent or misunderstood teachers in the Irish system.

I posed a question before about rounding. As in, round the below number to the nearest two decimal places:

1.564987

In my experience, roughly half of (Irish) people will give the incorrect answer of 1.57. Foreign people don't seem to have this issue.

muboop1

Chemistry Ftw wrote: »

Your changing it now... if you type 6÷2(1+2) you will get one! try it. If you type 6÷2x3 you will get 9.

No you dont...

Guys, please check this link/ quote.... link: http://en.wikipedia.org/wiki/Order_of_operations

Quote state that "Powers or Orders, and since multiplication and division are of equal precedence, M and D are often interchanged, leading to such acronyms as BIMDAS, BODMAS, BOMDAS, BERDMAS, PERDMAS, PEMDAS, PEDMAS and BPODMAS."

You do not differentiate between the two... Guys, this is basic sh1t here... think about it!

Opinicus

Shane732 wrote: »

48÷2(9+3)=

miscers unite!


"PEMDAS"
"Who?"

https://www.youtube.com/watch?v=SB3Ekgt1pHw

Yahew

I see

6÷2(1+2)

as

6÷2 * (1+2)

google sees this as equivalent to

(6 ÷2 ) * (1 + 2)

due to, as the man said, associativity. Thats certainly how I would see it in my head.

9

By removing the * for multiplication the eye is drawn to the parenthesis, but thats to read it wrong.

muboop1

nickcave wrote: »

It my work (MSc Applied Maths) I never use the ÷ symbol, nor do i find that anybody does. We also never use BOMDAS or BODMAS or any rule like that.

That said, we all know that the reason there's confusion over whether multiplication come before division or vice versa is that division by a term is simply multiplication by it's inverse. This is always the way division is dealt with in professional maths.

So,

6 ÷ 2(1 + 2) =

6 x 2(1 + 2)^-1 =

6^-1 x 2(1 + 2) =

(1/6) x 2 x (1 + 2)

And what is the answer now? Since multiplication is associative, it doesn't matter what the order is.






(Hint: It's 1)

No.

nickcave

28064212 wrote: »

Why are you grouping 2(1+2) together to get the inverse? Do you agree that 2(1+2) is shorthand for 2 * (1+2) and they are exactly equivalent?

Are you suggesting I take the inverse of 2 alone and get 6 x (1/2) x (1+2) = 9?

Or that I take the inverse of (1+2) alone and get 6 x 2 x (1/3) = 4?

(*tears up thesis*)

No, trust me, if you write A ÷ BCDEFG, you mean A divided by everything to the right of it unless there is delimitation with brackets e.g. (A ÷ BCD)EFG

There are no brackets delimiting the ÷ operation.

The OP's question is slightly ambiguous, but not really. In my writing and certainly in programming in (MATLAB etc.) we delimit everything to avoid ambiguity and for debugging etc.. Even still, the answer is definitely definitely 1.

Didn't know that Ronnie Drew knew Math

nickcave

muboop1 wrote: »

No.

Nice troll.

nothing

I've seen this elsewhere, with the 48/2(9+3), basically the notation is badly written deliberately for trolling purposes... For that one both 288 and 2 are correct answers, but you would need to give more distinction about whether the bracketed part is a denominator or numerator.

Same thing here, both 1 and 9 are correct until more rigorous notation is given.

Keen2win

Shane732 wrote: »

Is there a link to the question??

I'd like to laugh at people!!

I was trying to put a link to it and there doesn't seem to be a way...

It was asked by this fella
http://www.facebook.com/home.php#!/mike.carras?sk=questions

Just click "asked" at the top right and you should see it.

Yahew

Just use parenthesis to disambiguate - the man speaks sense.

28064212

nickcave wrote: »

No, trust me, if you write A ÷ BCDEFG, you mean A divided by everything to the right of it unless there is delimitation with brackets e.g. (A ÷ BCD)EFG.

So you're saying that 2(1+2) is not the same as 2*(1+2)? It's actually (2*(1+2))?

JustAddWater

Deleted User wrote: »

Didn't know that Ronnie Drew knew Math

And nick cave!!

abelard

The answer to

6
- (1+2) is obviously 9
2

The answer to

6

---

is obviously 1
2 (1+2)


Is the whole confusion not just because it had to be represented in an illogical manner on one line? There is no purely logical way of differentiating between the reading which results in 9 and the reading which results in 1 when it is expressed on a single line. Whether you want to rely on rules like BOMDAS or BEDMAS or whatever, since multiplication and division are associative, neither comes first. The BOMDAS rules and their ilk did not develop as there is a single most logical way of performing operations in mathematics, they developed as they represent the most logical way of performing operations ON THE WAY WE NOTATE MATHEMATICS.

The whole problem is in the notation. Surely this is not notated in such a way as to have a single logical way of performing operations in our notation system?

nickcave

28064212 wrote: »

So you're saying that 2(1+2) is not the same as 2*(1+2)? It's actually (2*(1+2))?

No, I said that 6÷2(1+2) = (6)÷(2(1+2)) unless there is some other delimitation.

Yahew

abelard wrote: »

The answer to

6
- (1+2) is obviously 9
2

The answer to

6

---

is obviously 1
2 (1+2)


Is the whole confusion not just because it had to be represented in an illogical manner on one line? There is no purely logical way of differentiating between the reading which results in 9 and the reading which results in 1 when it is expressed on a single line. Whether you want to rely on rules like BOMDAS or BEDMAS or whatever, since multiplication and division are associative, neither comes first. The BOMDAS rules and their ilk did not develop as there is a single most logical way of performing operations in mathematics, they developed as they represent the most logical way of performing operations ON THE WAY WE NOTATE MATHEMATICS.

The whole problem is in the notation. Surely this is not notated in such a way as to have a single logical way of performing operations in our notation system?

Yeah, its not a problem with mathematics bit with the notation system, as the answer is ambiguous.

muboop1

nickcave wrote: »

Nice troll.

Hardly I have presented my evidence. Follow bomdas rule thingy. Or (B)(O)(MD)(AS) as it should be presented.

6/2(1+2) = 6/2*(1+2) = 1(6/2*(1+2) same as = (6/2)*(1+2) = 9... hell put it into you calculator just as you see it, then put it into excel, then matlab! I have done all 3 just to verify (meant to be studying better alternative). This is most certainly equal to 9.

You could argue that it means 6/(2*(1+2)) but that seems a little irrational to me. why? because 2(2) has always meant 2*2. I have never witnessed any different. As such the equation would read 6/2*(1+2) = 9