Poll

What is 6÷2(1+2)?

1
9 (42.9%)
2
0 (0%)
3
0 (0%)
4
0 (0%)
5
0 (0%)
6
2 (9.5%)
7
0 (0%)
8
0 (0%)
9
10 (47.6%)
10
0 (0%)

Total Members Voted: 21

Voting closed: July 27, 2011, 12:45:52 PM

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Author Topic: Does this in your head.  (Read 13697 times)

« Reply #15 on: October 25, 2011, 12:19:25 AM »
It's 1. It's 1. Darn it the answer is 1. Operations in parentheses are always handled first. (as for the linked video which I didn't watch, the answer should be 2)

People will ask whether the equation is poorly written, or ambiguous, or why TI-whatever calculators give the wrong answer. You know what, I don't care anymore. It seems people look for any reason to avoid that unflinching rule that parentheses are dealt with first. Including changing 2(3) to 2 * 3 and then claiming that since multiplication has the same precedence as division, that we should go left to right. The problem there is that the parentheses were downgraded to multiplication. I strongly believe that 2(3) = (2 * (3)), not 2 * 3. Here's a better example, let's change that 3 to y. We have 2y. That's (2 * y), not 2 * y. Therefore the equation is 6 / 2y. If you think the answer to that is 3y, I weep for you.

This should also teach you to put everything in parentheses when dealing with a TI-whatever calculator. It's probably giving the wrong answer because it can't see 2(3) as (2 * (3)), or because it thinks the wrong behavior is more intuitive.
You didn't say wot wot.

Luigison

  • Old Person™
« Reply #16 on: March 12, 2013, 02:51:43 PM »
Sorry for the bump, but this problem just first page on digg and undoubtedly has been making the rounds on Facebook: 

http://www.slate.com/articles/health_and_science/science/2013/03/facebook_math_problem_why_pemdas_doesn_t_always_give_a_clear_answer.single.html
“Evolution has shaped us with perceptions that allow us to survive. But part of that involves hiding from us the stuff we don’t need to know."

CrossEyed7

  • i can make this whatever i want; you're not my dad
« Reply #17 on: March 12, 2013, 11:49:39 PM »
Quote
“To my mind,” says Grabiner, “the major deficit in U.S. math education is that people think math is about calculation and formulas and getting the one right answer, rather than being about exciting ideas that cut across all sorts of intellectual categories, clear and logical thinking, the power of abstraction and a language that lets you solve problems you’ve never seen before.” Even if that language, like any other, can be a bit ambiguous sometimes.

^^^
"Oh man, I wish being a part of a Mario fan community was the most embarrassing thing about my life." - Super-Jesse

« Reply #18 on: March 18, 2013, 07:46:56 PM »
This isn't really that interesting as I'm assuming everyone here can multiply, add and divide numbers under ten. This is just a test to see whether someone remembers a particular syntax for operation precedence, which mathematicians probably don't care about. It's better to just use parenthese to avoid misinterpretations/mistakes.

WarpRattler

  • Paid by the word
« Reply #19 on: March 18, 2013, 09:33:00 PM »
More than half the people who have voted in this thread have gotten the question wrong. That's absolutely "interesting," and why it's been brought up over and over.

« Reply #20 on: March 18, 2013, 09:50:35 PM »
But the only "interesting" thing is whether or not you do (6/2) * (1+2) or 6/(2*(1+2)). Which again, is just some boring syntactical thing, not really anything regarding mathematical understanding.

CrossEyed7

  • i can make this whatever i want; you're not my dad
« Reply #21 on: March 19, 2013, 01:42:03 AM »
Exactly. Personally, I do find discussions about syntax like this really interesting, both in math and language, but debating the distinction between synecdoche and metonymy is a very different thing from reading or writing a great novel; likewise, examining the history of the obelus symbol and arguing over notation conventions has little to do with real math.
"Oh man, I wish being a part of a Mario fan community was the most embarrassing thing about my life." - Super-Jesse

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