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This math problem is actually driving multiple message boards across the internet insane.


Just to see the commotion...
http://forum.bodybuilding.com/showthread.php?t=133389973
http://www.physicsforums.com/showthread.php?t=488334
http://forum.grasscity.com/general/787504-...72-9-3-%3D.html
http://www.basilmarket.com/forum/1981713/0/48293__288.html
http://niketalk.yuku.com/topic/294672/48-2-9-3?page=1
http://www.wallstreetoasis.com/forums/48÷293
To see more of the commotion:
http://www.google.com/#sclient=psy&hl=en&s...c9f4fa6ed867460

What do you think?
Discuss.

The answer is 2 if you follow the parenthesis rules.

48÷2(9+3) = 48÷2x(9+3)

So...

48÷2x(12)
48÷24
48÷24 = 2

This post has been edited by Lebon14 on Apr 8 2011, 05:04 PM

What? No. Correct me if I'm wrong, but aren't you supposed to go from left to right?
You do the parentheses first, so 9+3=12.
Which leaves you with 48÷2*12
Then you go from left to right.
48÷2=24.
24*12=288.

Oh yeah, right. Dumb me.

EDIT

But dunno why, the calculators that gives 2 as an answer must have gone from right to left like me above. But that's where "2" as an answer come from.

Damn, my maths are very rusted >_<

This post has been edited by Lebon14 on Apr 8 2011, 05:06 PM

How do I put it...

Some calculators are "dumb", not in that they can't compute correctly, because even an incorrect output can be logical based on how the input is solved...That of course can either be right or wrong, depending on whether the rules of "PEMDAS" (Solve an equation in order of Parenthesis/Exponents then Multiplication/Division then Addition/Subtraction) are followed, and the rules can only be followed by a calculator if they've been programmed sufficiently...

After all, the calculator is still bound by the algorithms set in place by a human programmer...If they don't account into the specific fact of how an equation is supposed to be solved by order of operations, then the calculator will just solve in order of input (Left to right)...The same thing can arise with how the symbols are used, like whether or not a calculator will acknowledge a number multiplied by a parenthesis without the multiplication sign as an implied multiplication or something else...

Limitations on the actual calculator itself or a change in settings might also hinder this oversight...A change in settings is my guess on why two Texas Instrument calculators would give different answers...I forget what it's about...

2 is the answer, anyway...If you can't figure this out using your basic algebraic skills without fact-checking against a calculator, then you're f**king stupid and dependent on technology...

This post has been edited by MidnightViper88 on Apr 8 2011, 05:26 PM

Can I see how you got 2, please? Thank you.

That's right, nevermind; I got ahead of myself, so the ultimate answer I said in my last post is wrong...

Great, who's the f**king moron now?

Order of operations is first priority, stack work left to right as you go the order

48/2(9+3)
48/2(12)
24(12)
288

This is obviously less of an algebra issue as it is a calculator programming issue...Weird indeed...

[edit]The incorrect way, to get two, you would have to compute things out of order, like so...

48/2(9+3)
48/2(12)
48/24
2

I think with the case of the latter, it has to do with a programming issue with the "implied" multiplication of the two in front of the parenthesis...Stick a multiplication symbol between 2 and the open parenthesis, and this programming paradox wouldn't exist...[/edit]

This post has been edited by MidnightViper88 on Apr 8 2011, 05:49 PM

Thing is there's a bit of ambiguity here. If you follow PEMDAS strictly then it's 288. But the problem is there's a convention that multiplication by juxtaposition (e.g.: placing two values beside eachother) will sometimes take precedence over division. If you follow this additional rule than the answer is 2.

The following article should clarify this:
http://www.purplemath.com/modules/orderops2.htm

Excerpt:

This post has been edited by icedagger on Apr 8 2011, 05:58 PM

f**k me, take me back to Calc III where I can really screw my mind over...

Great this gonna screw me over in class from now on. I'll be constantly second-guessing myself when i wouldn't have before. Fuken intranetz! lol

This post has been edited by bROCKoLEE on Apr 8 2011, 07:23 PM

well.....i was always told to multiply before i divide...

i got 2.

however, im aware that they're equal in terms of weight...

This post has been edited by Sensation! on Apr 8 2011, 07:27 PM

I dunno about PEMDAS, but it's 288 from basic math. It's weird that my calculator shows 2. D: Now I'm worried of using it to get through my university days.

Unless the expression is 48÷[2(9+3)], it can't be 2 afaik.

It seems that some calculators set the parenthesis to have higher precedence than others. I can see how it gets 2 as others in this thread had pointed out. I am sure you can find that in that specific calculator's manual. Parenthesis will imply a multiplication in these type of calculators.

What I want to test on these calculators is, run the following:

48÷(9+3)2

If that still gives 2, then we know for sure the parenthesis operator followed by or preceded by any operands will imply a multiplication with higher precedence than a normal multiplication "x." However, if it returns 8, as it should be, then the parenthesis operator implies a higher precedence multiplication only when an operand precede it.

This post has been edited by Perry on Apr 8 2011, 08:01 PM

^ It gives me 'syntax error'... O_O

This is gonna change the way I look at math forever...

No, calculus will teach you how to look at math differently, where you can indeed divide by 0 and ±∞ can be something of a real number solution, thanks to limit approaches...

This is just ambiguous calculator programming...

This is gonna change the way I look at math calculators forever...

Oops, fixed.

I saw this in FB yesterday but had no idea that there are so many people out there going crazy over this..... Shows you how even the simplest things can be made interesting, eh?
For me, I got 288...... The brackets always come first...

The answer is 288. Anyone who says otherwise needs to go back to elementary school and relearn the order of operations.

The parenthesis rule only applies to shit inside the parenthesis. Outside, you just treat it like regular multiplication.

48/2(12) = 48/2*12

When faced with multiple multiplication/division operations, you simply go from left to right.

I don't know much about programming, but any calculator that gives "2" as the answer is wrong because it violates the laws of mathematics. All there is to it.

P.S. I won't do this myself since I don't see the point in wasting my time on something so simple and obvious, but put down your little TIs and try using software that actual mathematicians, some engineers, and scientists use (Mathematica, MATLAB, etc.) and see what you get. I'm going to guess it's 288.

This post has been edited by Nappy Hared Azn on Apr 9 2011, 12:57 AM

Well, I can tell you that using the calculator included in Maplesoft, 288 is the answer...And this is the calculator for software that's programmed to calculate numeric computations and visually graph extremely complicated equations to three-dimensions...f**k if it can't solve simple algebra...

I've never used Maple, but I know tons of people* who use it, so I'm also sure it can do simple algebra.

* - People who actually use math on a daily basis.

My wife- the Techpriestess Enginseer posted the answer in MT thread.

This post has been edited by JKaiba on Apr 14 2011, 07:26 AM

Damn I can't believe this trivial math problem can get me into thinking so long about what's wrong.

The answer is 288, you are not supposed to do it backwards, you need go from left to right.

Not really; It's good that people are thinking things through instead of only relying on what the calculator says...

Of course there are complex things a calculator can compute for us in a second that used to take a literal long time in ye olde days, but when it comes to basic things like this and people get confused by the calculator with hand method makes it clear, it gets kind of pathetic...

I've been wondering why people talk about calculating things from left to right anyway.

Because AxB = BxA (in most cases, but I'm no mathematician so correct me if I'm wrong). So as A+B = B+A, and A-B = -B+A.

So in this case, no matter left to right or right to left, it'll still be 288.

AxB =/= BxA

for matrix multiplication, they are not communtative I remember