So earlier today on Facebook I noticed a friend of mine answering one of those annoying question/poll things they implimented a while ago. It was a simple maths problem yet the majority of people that answered [majority of 100000 people] managed to get it wrong.

So tell me, what's the answer to 6/2(2+1)?

uh

how could you get that wrong

I don't know, but somehow 600000 people did.

Order of operations, b****. Also, I love how this is a public poll.

huh, i was expecting some kind of trick question

Why? The answer is pretty simple. Many people were taught the order of operations using mnemonics such as PEMDAS (Parentheses, Exponents, Multiplication, Division, Addition, Subtraction). However, when they were taught this, they often do not make the distinction that multiplication/division and addition/subtraction are to be treated on the same level, not as separate levels. Thus, you end up with the other, incorrect answer here.

I know this happens because it's exactly how I was taught in middle school, and luckily my passing interest in programming at the time taught me otherwise.

I reckoned it was more because of the interpretation of where the brackets sit in horrible text notation.

Where's the 42 answer?

since theres an edit in the original post i'm betting the problem changed

>.>

Yeah it's because people read that as

If it was written as 6 / 2 * (2 + 1) I'd have gotten it correct. Unfortunately due to mental hiccups, I automatically replaced 2(2+1) with 6 before even looking at the rest of the equation.

This is why I'm always as explicit as possible (within reason) when writing down equations.

Agh, not this damn herp-a-derp equation again (I saw it on another forum recently). At least a lot more people are getting it right here than the last place I saw it.

And yeah, kinda going on what Detty said, no self-respecting engineer, math nerd, etc. would ever write an equation like that.

I'm still counting so I can't answer the poll yet but hold on

This is what most people probably do. They resolve the parenthesis node and move left instead of moving from left to right.

The precedence of multiplication and division isn't a standard. The way you read the equation depends on where you went to school.

If anybody showed me this the first thing I would do is ask which way they intended to write it.

Do people in the UK actually say "maths"?

Yeah, and they call sports 'sport'. Figure that out.

These are the kinds of questions that are best suited for quizzing me. Massassi should reserve them for me for humorous reasons only. I was decent at math as a kid but I graduated from HS back in '89 and had no further math education until rather recently. I did always understand that Algebra was the way to solve practically any number related problem you routinely come across and I use it all the time to figure things. About 18 years ago I was attending a leadership course and we were in the map reading portion of the class. All recruits do map reading and land navigation training in basic but they are considered perishable skills so they are routinely retaught in various professional development courses. Of course the subject was fairly mundane to me. I was an Infantryman and routinely used those skills. Bored and knowing that given two grid coordinates to two points on a map, I had all the information I needed to determine the distance between the points without even looking at the map. Essentially I figured the correct manner in which to subtract the x and y axis of the two points in order two frame them as A^2 + B^2 = C^2. A few months later I was required to take a TABE (Test of Adult Basic Education) as a routine part of inprocessing at Fort Richardson, Alaska. Some of the math was so old to me that I had to figure problems in a more complicated manner to confirm that I remembered the way to calculate them. For example, regarding division of fractions I knew there was something about "recipricol" or "cross multyplying" but wasn't quite sure so I figured the answer, probably like 1/2 divided by 2 which has an obvious answer, to refresh myself on how I was to do it. It worked and I remembered the "proper" way to figure the problems. I got a 12.9 in each area which was the max. I guess fully HS competent and ready for college courses.

So with regard to this problem I admit I first saw it as 6 divided by 2(2+1) but that didn't seem right and I knew that the better way to look at it was to distribute 6/2 with (2+1) which, of course, gives you 6 plus 3.

Yes, because its Mathematics and not Mathematic.

WHY

I saw a link to a debate on an IGN forum. This is the new 0.999... = 1 debate, but for dumber people

9. No mental hickups, even though I'm usually quite terrible at mathematics.

This is indeed how I read it.

Mostly because of having to use one-dimensional input. If I went using Brackets Of Division Multiplication Addition Subtraction, then I suppose I should have got nine. But... erh. I look at the full equation, interpret it, simplify. And that's how I interpreted it.

Honestly, I kept second-guessing myself because it's written more or less ambiguously as it is. And of course I pick the HURR answer.

This is how I did it in my head

6/2(2+1)
6/2(3)
3(3)
9

Let's just force everyone to use prefix notation and this wouldn't be a problem...

Indeed, this is so stupid.

Baconfish, do you write equations like this in daily life?

Exactly as I read it. The notation is ****e.

No, I'm not daft enough to do that.

(6/2)(2+1) would be a less ambiguous way to write the equation given the limitations of the text field but it becomes much too simple. This is exactly the type of problem that would show up on an elementary level math test, even in bad notation, to ensure that students understand the concepts they're being taught. It tests your critical thinking as much as it does math.

But why post it like this in the first post!

You and your habit of luring people into a false sense of security.

I don't remember seeing horrible equation wtiting like this ever in elementary school.

Not in textbooks, no, but when your teacher is typing out the tests and quizes themselves on an Apple IIe their notation is going to resemble the equation in this thread. Not to mention it reinforces the order of operations as Matty described earlier.

Also if you've ever used a TI-83 you should not get this question wrong.

I don't understand how the answer to this could be anything other than 9.

It couldn't possibly be the way Pommy wrote it without another set of parentheses.

Ah, fond memoriex. I had one in high school, and played Tetris and other games on it all the time. Even in math class. And every other class.

Of course I was jealous as all get out of my classmate Carter, who had a TI-86 and could thus play freakin' Mario.

I had (and still have) a ti-86, yes the games were much better

You're right, but people still read and write it that way because other people read and write it that way. It's akin to people writing "alot" or "allright" or "could care less" -- it's technically wrong but people get used to it and then insist that it's correct because it's common knowledge.

For the record, I also read it like that at first, mainly because when I write equations on the computer or on a TI-89 I explicitly write all parentheses (a habit to avoid the problem above), so whenever I see something that LOOKS like it was written wrong, I automatically (subconsciously) try to fix it. To make it more evident, imagine that it was 6/x(x+2). I would write that as 6/(x(x+2)). It "looks" wrong because if it was meant to be 6/x times x+2 I assume it'd be written 6/x * (x+2). Because the parentheses is not there and it looks like the person wanted to combine the x terms together I have the urge to "correct" it mentally so I just add the parentheses in assuming the person who wrote the equation was writing it wrong, rather than realizing that it was actually intended to be written like that and that I'm actually wrong.

No it isn't.

Many people are taught BEDMAS. Many people are taught PEMDAS. There is no standard for the precedence of multiplication with respect to multiplication ('officially' they have equal precedence.)

'1' and '9' are both correct answers for this problem. The statement of the problem is deliberately ambiguous and says absolutely nothing about mathematical ability.