Question

[»Lynx]

Hrmm Edited April 28, 2011 by Lynx

[Dr Brain]

Is this a serious question? or was it edited into insanity?

[»Lynx]

Serious question, lots are arguing about it on Facebook. Would be interesting to see what you guys say the answer is.

[Samapico]

Division and multiplication have the same priority and should be calculated from left to right

 

6÷2(1+2) = 6/2*(1+2) = (6 / 2) * (1+2) = 9

 

Also, division by 2 can be interpreted as multiplying by (1/2), so:

 

6*(1/2)*(1+2) still equals 9

 

 

The Facebook people are dumb

[Hakaku]

Afaik, you're suppose to complete the parentheses first, so you end up going from 6÷2(1+2) to 6÷2(3). At this point, the parentheses are useless, so you can rewrite it 6÷2×3. Since there are no explicit parentheses around 2×3, you have to go by left-to-right order, meaning that 6÷2 gets calculated first, then 3×3, which is why you end up with 9.

 

I think the confusion stems from wanting to calculate the parentheses with its closest multiplicator, since they're seen as a pair - which probably stems by confusion with additions and subtractions, as in 6+2(1+2). And so some would argue that we have to follow 'PEMDAS' order and complete the calculation with the parentheses first. In reality though, it's just a multiplication, and if you fill in the blank, 6÷2×(1+2), the association becomes less clear.

 

Edit: Sama beat me

[Corey]

How could anyone possibly come up with 1?

[Cheese]

because it looks a lot like 6 / (2*3)

[Emit]

...did no one take order of operations or something

[»Purge]

lol @ this

[»Lynx]

You'd be surprised.

 

Me: ‎(6 / 2) * (1 + 2) = 9... How'd u get 1? lol

Me: Oh, you done 6 / (2(1 + 2))

Friend: basically chris i did it right

Other Friend: lol nah multiplication is priotity over division

Me: Actually, I'm pretty certain they share precidence, hence why multiplication by 0.5 == / 2

 

... Then the whole Order of Operations thing came into it (BODMAS/PEDMAS) but then people were claiming you should always work from the closest to the parenthesis. I was never brilliant at Maths (I still got 9) and I figured you nerds would quickly get it.

Edited April 29, 2011 by Lynx

[Dr Brain]

http://lmgtfy.com/?q=6%C3%B72(1%2B2)

[007paulwall]

its 1 because 6-2 = 4 and 4 - (1+2) = 1

 

the answer is 1

 

 

/topic

[Ninja Cat]

It's obviously 9. But, will an airplane on a treadmill be able to takeoff? Edited April 30, 2011 by Ninja Cat

[Dr Brain]

Yes it will; see Mythbusters for a conclusive discussion.

[Samapico]

Also, this:

http://www.wolframalpha.com/input/?i=+6%C3%B72%281%2B2%29

[Ninja Cat]

Yes it will; see Mythbusters for a conclusive discussion.

 

I just looked for that Mythbusters article and saw the video. They did not answer the question at all.

 

1) Why did the plane move faster than the conveyer belt? Surely, that is generating it's own airflow and negating the original question.

 

2) What was the wind direction and speed relative to the aircraft at the time of the experiment?

[Dr Brain]

I don't know what you're talking about. I can only assume you have not seen the entire episode.

[Samapico]

Yes it will; see Mythbusters for a conclusive discussion.

 

I just looked for that Mythbusters article and saw the video. They did not answer the question at all.

 

1) Why did the plane move faster than the conveyer belt? Surely, that is generating it's own airflow and negating the original question.

That's the point... the wheels of the airplane are free wheels. In an ideal world, they wouldn't even have any friction, so even if you pulled a conveyor belt under it, it would have no effect on the speed of the plane. Of course, there is a bit of friction, but not enough to counter the pull from the propeller.

 

But a thing that did annoy me in that episode is that, from what I remember, they tend to mix up 2 completely different questions...

a ) The proper question: Can the airplane take off with a conveyor belt going at under it?

B ) The question they ask the pilot: Can the airplane take off if it is pulled by the conveyor belt at ?

 

Not sure of the exact wording used, but the question asked to the pilot can definitely be answered with "no", and then they make him look stupid because the conveyor belt actually doesn't pull the plane.

[NBVegita]

The reason why people get the answer 1 is due to multiplication by juxtaposition.

 

For example, If I were to write this statement:

X = (1 + 2)

X = 3

6 / 2x =

 

A lot of people might interpret that as:

6 / 2(x)

6 / 2(3)

6 / 6 = 1

 

Others may not use mbj so you'd get:

6 / 2(x)

6 / 2(3)

3(3) = 9

 

Keep in mind that the notation is terrible, but I believe a lot of people, using the juxtaposition that is familiar with variables, will multiply what is juxtaposed before completing a further operation.

 

Which is right? Well I can't find any evidence that conclusively states how mbj is treated in relation to ooo.

 

Note that some calculators will state the answer is 1, while others will say it's 9. Ultimately it comes down to how the application was programmed as to if 6 / 2(1+2) is interpreted as 6 / 2 * (1+2) or 6 / (2 * (1 + 2)).

 

Again the argument isn't if 6 / 2 * (1+2) = 9, it's if 6 / 2(1+2) == 6 / 2 * (1+2).

[Dr Brain]

Well 6/2x is 6/2*x, not 6/(2*x), so your argument sort of falls apart there.

[NBVegita]

No it doesn't.

 

Note I said:

 

A lot of people might interpret that as:

6 / 2(x)

6 / 2(3)

6 / 6 = 1

 

Others may not use mbj so you'd get:

6 / 2(x)

6 / 2(3)

3(3) = 9

 

 

Being that this has become a huge internet phenom with a lot of people on both sides, that means what I stated above is true, as a lot of people are interpreting it as I showed in case one. Simply put, some people have been taught that mbj takes priority over division and others have not. I've tried to find something other than "wiki answers" that says if mbj does or doesn't take priority and I can't. That doesn't mean that it does, but if someone is taught something mathematically that cannot be disproved, then how can you say they're wrong?

 

The whole reason why there is a debate is that any sane mathematician would write it as either (6/2)*(1+2) or 6 / (2*(1+2)).

 

Honestly if you can show a credible math publication that states mbj does not take priority in ooo, then I'll stop playing the devil's advocate.

[Dr Brain]

I have no idea what you mean by mbj or ooo.

 

In mathematics, implied multiplication doesn't have a higher precedence than explicit multiplication. Some calculators think it does, but they explicitly state in their manuals that it's done that way for convenience, and is not accurate.

[Dav]

This is a classic high school example of BODMAS though, it is intentionally confusing and ambiguous without applying the standard methods of working.

 

I seem to remember having 1-20 from your favorite textbook of these... used to find the repetition so unbelievably dull. no wonder I (attempted to) give up maths.

[Cheese]

just tell these fools that x and / are evaluated left to right and tell these fools to stfu

[NBVegita]

mbj - multiplication by juxtaposition

ooo - order of operation

 

Can you find me a sample manual for these online...it seems like an oxymoron to have a calculator give you a protocol, that they state is wrong, yet they do it anyway.

 

Most notably that it is actually MORE convenient to interpret 2(3) as 2 * 3 rather than (2 * 3).

 

All I'm saying is the fact that no one can produce a published math document saying that mbj or implied mult doesn't take precedence in ooo, I'm hard pressed to say that people who interpret it that way are wrong.