Can you do this simple maths problem?
- Thread starter Rathaus
- Start date
ParadigmShifter
Random Nonsense Generator
*runs away to proper maths thread*
To be sure my very first impression the first time I saw this was that it was poor notation and that the OP (this was the OP on another website) was a troll. But by now one can have had enough of hearing about it, and people have thousands of published textbooks, guidebooks from calculator companies, you name it. Nobody had a single published source of anything indicating otherwise. So the answer "2" is really more sensible by every approach, you'd KNOW that someone who wrote this by hand would also mean 2. My first impression was this thread didn't need to be made here either but what are you going to do.
I am always impressed with the practicality of mathematicians. I once knew one who was constipated, but worked it out with a pencil.
ParadigmShifter
Random Nonsense Generator
bdum tish?
What's purple and commutes?
What's purple and commutes?
Spoiler :
The really universal conclusion everyone reasonable took from this discussion elsewhere is that the British are completely off their rockers for the acronym "BODMAS" or whatever other similar perversion they learned. It's definitely P for Parentheses, not B, not to even get started on the O nonsense
And did you hear about the anagram of Banach Tarski?
Spoiler :
To be honest i dont really care what the ultimate and only correct answer is, and im pretty certain the OP doesnt care either. So why battle. It isnt solvable. Apples vs Bananas.
Well sure the OP doesn't care. It's a computer programmer thing. Another way to look at it:
int answer calc(postcount)
{//these are brackets for the limey ruffians out there
postcount++;
answer = sqrt(1+postcount*calc(postcount)); //this is cool here
}
correctanswer = -1+calc(1);
int answer calc(postcount)
{//these are brackets for the limey ruffians out there
postcount++;
answer = sqrt(1+postcount*calc(postcount)); //this is cool here
}
correctanswer = -1+calc(1);
jtb1127
Deity
Parenthesis
Exponents
Multiplication
Division
Addition
Subtraction
48/2(9+3)
48/2(12)
48/24
2
Am I missing something?
jtb1127
Deity
Or I guess it could be if you do pemdas is a different order
48/2(9+3)
48/2(12)
24(12)
288
48/2(9+3)
48/2(12)
24(12)
288
warpus
Sommerswerd asked me to change this
The equation is this: 48÷2(9+3)
You are dividing 48 by 2, not by 2(9+3). If you were dividing by all of that you'd need brackets around it. There aren't any, so only 2 is in the denominator.
The issue is NOT whether multiplication comes before division. The issue is what is meant by the equation. There are no brackets around 2(9+3), so you have to assume that only 2 belongs in the denominator.
warpus
Sommerswerd asked me to change this
Again, it's not an issue of which operation is performed first. The issue is what is meant by the question.
Archbob
Ancient CFC Guardian
The two next to the parenthesis 9+3 makes me think you multiply first, but I guess not.
But you do, and that is correct. It's called implicit multiplication, it's like how you shouldn't separate variable coefficients when interpreting confusing notation either. That's about the only thing that actually remains really interesting to me about this. Places on the Internet where supposed "experts" came in to answer one way, saw droves of people follow and decide that must be "right" no matter which way it actually was. It's like a conformity effect. Though of course the "everyone in your country sucks and didn't learn right when they were 8 years old" was usually still common. But it surprises me that someone like just above will go against their common sense and/or what they learned and be all, "I give up, I must suck at math, lol."
It does legitimately appear people were taught differently in different places and languages, don't get me wrong, that makes it a little interesting. But I'd still say you're especially not wrong if you answer 2. And warpus you're not getting what that means, it is an order of operations thing since implicit multiplication has precedence over other arithmetic operations. Algebra textbooks even for young students will explain how 2x/3y is equal to (2x) / (3y) and obviously not 0.667xy - though again, if one of you actually has a British/Canadian text or whatever stating otherwise please actually post it, I'd think that could part of reasonable debate on CFC as opposed to less civilized places on the net. And on top of that again that convention is close to universal in any scholarly and professional work, practically every physics, chemistry, engineering, etc... books will write formula using implicit multiplication rules. I can see just insisting the notation is bad and the OP (generic OP) sucks, which if it wasn't that the point of such a thread is to bicker would be the end of it, but that a person will just change their mind and give up, especially in favor of the answer that has less reason to it, is pretty interesting.
innonimatu
the resident Cassandra
- Joined
- Dec 4, 2006
- Messages
- 15,375
No, you do not. You do not have to assume anything. I don't think I used a single book in university which printed equations with divisions in a single line. I don't think the maths books presented any axiom regarding the ordering of division and multiplication. I take it to be merely a (mathematically unimportant) convention which can vary.
Yes, that's the first thing, an equation looking like the one in the OP will never appear outside of a child's homework, but of course that's part of the trollishness of the problem.
Well, I would point out if you'll believe me that as this came up elsewhere on the net there certainly are people who actually had math textbooks down to and including the original children's level, like for 10 year olds, which explicitly stated the convention for implicit multiplication. That's outside of all the examples already mentioned of unversity level texts across many fields that use the same convention by default for tons of equations, people really aren't thinking when they don't realize how ubiquitous the convention is and you'll never see an equation written the other way to mean something else. For actual math books I could probably go find one of those images if someone really wanted to, I wouldn't have the books themselves but scans/photos that people were posting but don't really feel like it and people probably wouldn't agree it settles anything. And in turn I'd still really be interested to see if someone has said infamous "British text" that taught them the other way - with thousands of people on other Internet sites, not a single person found a reference that suggested the 288 way was correct.
warpus
Sommerswerd asked me to change this
Guys.. listen.. If somebody writes 2/5*5, I am not going to assume this means 2/(5*5). That doesn't make sense.
Unless you put the whole term in brackets, it does not belong in the denominator.. unless you do it like this
Unless you put the whole term in brackets, it does not belong in the denominator.. unless you do it like this
Code:
2
---
5*5Putting in the multiplication star means it's not an implicit operation, no one is disagreeing about that.
If somebody writes 2/5x, you get:
2
---
5x
Yes, it's a conventional thing, yes, it's probably something that people in different countries have a little different culturally. But I'd like to ask people to at least actually try and find a single published example of this anywhere that supports the 2/5x = (2/5) * x, even for kids. On the other hand that are thousands of texts, journals, etc... across pretty much all technical fields where formulas are written all the time as wx/yz = (wx) / (yz) and the like, and nobody would ever, ever write wx/yz = wxz/y.
If somebody writes 2/5x, you get:
2
---
5x
Yes, it's a conventional thing, yes, it's probably something that people in different countries have a little different culturally. But I'd like to ask people to at least actually try and find a single published example of this anywhere that supports the 2/5x = (2/5) * x, even for kids. On the other hand that are thousands of texts, journals, etc... across pretty much all technical fields where formulas are written all the time as wx/yz = (wx) / (yz) and the like, and nobody would ever, ever write wx/yz = wxz/y.
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