48/2(9+3) = ?

[Troylee]

288? Following PEMDAS, I get 2:

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

The reason why some people are getting 288 is that they're forgetting that there's an invisible multiply sign in the expression.

Honestly though, if I ever saw this I would apply a facepalm. It's not good notation and like you're seeing, it's ambiguous without proper use of parentheses and will confuse people. It's better notation to say

 

[Wy Renegade]

I'm certainly no math guru, and I'm not even all that fond of math, but as I said, on the standarized tests we use nation wide in this country, the correct answer is 2. Disagree all you want, I'm just telling you what the national standards board says is the right answer.

 

[bct15]

The function takes the form

C(f(*))

Where C is a constant 48/2 and f(*) is a constant 9+3.

Rewriting
(C)(f(*)) = (48/2)(9+3)

Applying the correct order of operations

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

A least that is what the I have learned while working on my PhD in mechanical engineering. With knowledge in tensor calculus, multiple variable partial differential equations, differential geometry and the sorts. All much more advance than basic calculus in this case basic algebra.

For those of you who aregetting 2, the function has been incorrectly defined in your calulator as 48\[2(9+3)].

Trust me the correct answer is 288 as defined by the original poster.

 

[Paul_N]

288? Following PEMDAS, I get 2:

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

The reason why some people are getting 288 is that they're forgetting that there's an invisible multiply sign in the expression.

Honestly though, if I ever saw this I would apply a facepalm. It's not good notation and like you're seeing, it's ambiguous without proper use of parentheses and will confuse people. It's better notation to say

Uh nope.....:tongue:

"A common technique for remembering the order of operations is the abbreviation "PEMDAS", which is turned into the phrase "Please Excuse My Dear Aunt Sally". It stands for "Parentheses, Exponents, Multiplication and Division, and Addition and Subtraction". This tells you the ranks of the operations: Parentheses outrank exponents, which outrank multiplication and division (but multiplication and division are at the same rank), and these two outrank addition and subtraction (which are together on the bottom rank). When you have a bunch of operations of the same rank, you just operate from left to right. For instance, 15 ÷ 3 × 4 is not 15 ÷ 12, but is rather 5 × 4, because, going from left to right, you get to the division first. If you're not sure of this, test it in your calculator, which has been programmed with the Order of Operations hierarchy. For instance, typesetting this into a graphing calculator, you will get:"

 

[benny z]

actually, the calculators disagree...

 

[Reggie]

Ok, I understand now that those who answer 2 are based on the distributive property rule or "multiplication by juxtaposition." That rule dates back to the 15th century, and while the PEMDAS (left to right) rule predates it, the fact is both the rules exist and both notations interpret things differently. The solution however is to make the main problem clearer -- is it (48/2)(9+3) or is it 48/(2(9+3))?

I'm a PEMDAS kind of guy and given that problem, will always compute it as 288. ;)

Multiplication by juxtaposition -- I learn something new everyday! Thanks for the post!

@benny z, that pic is golden! :D

 

[Paul_N]

TI-86 is newer..we'll go with that one...lol

 

[benny z]

TI-86 is newer..we'll go with that one...lol

...and macbook pro is newer yet.

:p

 

[sdsocal]

A least that is what the I have learned while working on my PhD in mechanical engineering. With knowledge in tensor calculus, multiple variable partial differential equations, differential geometry and the sorts. All much more advance than basic calculus in this case basic algebra.

I'm sure many of us on here are educated, but that does not make us the definative answer to the problem nor does the education we have or are receiving mean that we have been taught correctly. This is what makes this such a great discusion in my opinion is that depending on interpretation of the written expression, present and past mathmatical rules / laws / theory the answer varies. I love that the calculators Beeny showed that are 1 Model apart are different in their answers reflecting truth in the article I found and posted.

For me it is much like when writting a computer program - I always need to make sure that I get specific info from the source in how the problem should be performed and then translate that into linear code that gets the same answer and then test test test and test again.

This equation so much like our hobby of reefing. :bigsmile:

 

[CJO]

That's because he is using a TI. If he used a real calculator, like an HP48GX, he would get 288 every time :)

Also, sorry, Excel is not a great math tool. I think I might have a copy of Mathmatica around here somewhere.

CJ

 

[CJO]

Better yet. Use WolframAlpha, which uses Mathmatica as its basis for calculations:
http://www.wolframalpha.com/input/?i=48%2F2%289%2B3%29

CJ

 

[nixer]

as its written its 288

 

[clarky2120]

:confuse:

 

[bct15]

CJ I only mentioned my education to establish my credibility on the subject.

I went ahead and ran the problem (as stated by op) on various tools i use on a regular basis, with each giving the same result as my proof posted earlier.

MatLab

C++

MathCad (automatically rearranged)

TI's

Brandon

 

[greg0385]

:D :p

thats so funny that we had the same saying in my school, works great!!!
answer is 288, final answer !!!
i always loved math and science in school.

 

[drainbamage]

it seriously worries me if that is actually the answer on the standardized tests though (the 2 answer)....show's we're getting REALLY sloppy with basic math, at a fairly young age too :squigglemouth:

 

[greg0385]

oops it was suppose to be a reply to--- Please Excuse My Dear Aunt Sally. we used that saying at my school too.

 

[BigFeesh]

288? Following PEMDAS, I get 2:

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

The reason why some people are getting 288 is that they're forgetting that there's an invisible multiply sign in the expression.

Troylee has this on point
When in pemdas multiplying parenthesis with an outer number goes before division so it's 2

Nevermind working when I used pemdas I got 288
Then I used multiplication with juxtaposition and got 2 !
We need a math prof in here:tongue:

 

[nixer]

why? its really simple. you guys need to realize that once you do the parenthesis it doesnt remain that way.
48/2(9+3)
which is 48/2(12) is the same as 48 / 2 x 12

whats really classiic is when you see a multibillion dollar job run amuck because some ****** figured that when you do the metric to inch conversion they drop the remainder and just ignore it, which isnt a big deal in about 4feet over a few holes that are 1/16 over sized. but when your working 400 sets of holes in around 300 linear feet then sir after about 40 feet your off 1/4". you should of seen the look on that engineers face when i set him straight.

 

[drainbamage]

288? Following PEMDAS, I get 2:

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

The reason why some people are getting 288 is that they're forgetting that there's an invisible multiply sign in the expression.

Troylee has this on point
When in pemdas multiplying parenthesis with an outer number goes before division so it's 2

Nevermind working when I used pemdas I got 288
Then I used multiplication with juxtaposition and got 2 !
We need a math prof in here:tongue:

I really think if we get a math 'prof' in here, we're going to get 288.

If we get a math 'teacher' (k through lets say 8th grade) we'll get the 2 answer. I think as a nation if our mathematical literacy was better, we'd do better- but I'm a math nut, so I have a very biased opinion.