A simple but ambiguous expression

Question

Possible Duplicates:
Implicit multiplication order of operation
What is 48÷2(9+3)?

i am so confused after knowing different answer of this ques
48/2(9+3)
though google cal comes up with ans 288 but i have seen its answer 2 on some websites
please clear this confusion

A/BC can mean either (A/B)C or A/(B*C). Without explicit bracketing or without conventions establishing operator precedence it is ambiguous. — Bill Dubuque, Apr 30 '11 at 20:20
Why would different people want to know the answer to this banal expression? — Uticensis, Apr 30 '11 at 20:23
@flutty: The problem here is not with the math, but with the notation. Many people seem to think that this question does not have a clear answer because the mathematics hasn't been figured out. Really, the problem is that it isn't clear what is being asked, and the question could be interpreted as one of several different math problems. It's like saying "I have a red house and I have a blue house. What color is my house?"--the problem is that it's unclear which house is being talked about, not that people haven't figured out how to determine the color of a house. — Alex Becker, Apr 30 '11 at 20:24
SORRY EXPERTS...i know this is very irritating will take care of this from next time — fluty, Apr 30 '11 at 20:24
SORRY EXPERTS...i know repetition of such question is very irritating will take care of this from next time ... — fluty, Apr 30 '11 at 20:27
@Theo: This didn't actually start on Facebook, that's just one of the ways it's spread. It's an example of a meme, a quirky expression which spreads like wildfire on the internet. Information on it's origin can be found at http://knowyourmeme.com/memes/48293. — Alex Becker, Apr 30 '11 at 20:30
@ Zen: who are you talking to? Shouldn't comments left re: questions be addressed to the OP? or to answerers, about their answers. Keep the "Huh, this again" to meta. — amWhy, Apr 30 '11 at 20:30
@others: keep this discussion to Meta...And fluty, this isn't just about making the site interesting to experts. Bill's comment is the only one relevant to OP, and Alex's background is helpful too. — amWhy, Apr 30 '11 at 20:33
There must be a way to use this confusion in order to get huge discounts in shops..." What does this cost? 48$ $ $ for 2 pieces? Give me 9! No wait, I want 3 more!" --- "That will be 2$, sir, have a nice day." — Myself, Apr 30 '11 at 20:35
@Alex: Thanks. That contains way more info than I needed. The sentence "On April 27th, 2011, a Redditor posted a slightly different version to the “wtf” subreddit. As of April 29th, 2011, it has received 1281 comments, and has a karma score of 776" reads like chinese to me. But "wtf subreddit" seems to describe my reaction aptly. — t.b., Apr 30 '11 at 20:35
I created a meta thread for discussion of this and similar questions: http://meta.math.stackexchange.com/questions/2127/what-to-do-about-what-is-48-293-type-questions. — Alex Becker, Apr 30 '11 at 20:45

score 2 · Accepted Answer · edited Apr 13 '17 at 12:19

2

By standard convention, 48/2(9+3) is 288. Anyone who wants to be well understood should write either $\frac{48}{2} (9+3)$ or (48/2)(9+3).

Please don't ask this question again. Instead, look here, here, here, or here.

edited Apr 13 '17 at 12:19

Community

1

answered Apr 30 '11 at 20:25

davidlowryduda

91,687

8

What "standard convention" do you refer to? I don't believe that there is any such universally accepted standard. Indeed, that's probably the reason that it is such a popular question. – Bill Dubuque Apr 30 '11 at 20:42
@Bill: Unfortunately, the only response to what 'standard convention' I refer to is - the convention that 48/2(9+3) = 288. I learned this convention in school, and more importantly in programming classes. But before we get into an ultimately unfulfilling and most likely meaningless debate over whether or not there is a standard convention, I suspect we can both agree that this is apparently ambiguous to many people, but can be written in a clear way very easily with only one additional set of parentheses. – davidlowryduda Apr 30 '11 at 22:48
5

I don't expect authoritative answers on mathematical conventions from (grade/middle) school teachers or programming languages. Having a strong interest in the history of algebra, I've perused hundreds of (abstract) algebra textbooks from many different time periods. I don't recall a single (modern) author specifying any convention to resolve such ambiguities. Instead, they simply use brackets as need be to resolve the ambiguity. – Bill Dubuque May 01 '11 at 00:07

A simple but ambiguous expression

1 Answers1