So, calculator is un-reliable today?

[Vastor]

 

I don't know why people claim fx-570MS is right (most of these guys tell that their teachers said so ) , I mean:-

 

(translated from my comment there)

 

‎9 is right...

 

proof : ab = a * b, so 6 / 2(3) = 6 / 2 * 3 = 9.

 

(translated from my comment there)

 

so guys, which one is right?

[Fuzzwood]

First one is correct. 1+2 in brackets give 3, and then multiplication before division. The right calculator is a straight-on calculator and would be wrong.

[Vastor]

so, wolfram alpha is un-reliable too?

 

http://www.wolframalpha.com/input/?i=6%2F2%281%2B2%29

 

First one is correct. 1+2 in brackets give 3, and then multiplication before division. The right calculator is a straight-on calculator and would be wrong.

 

oh, btw, wat make the multiplication "must" happen before division?

[Fuzzwood]

I blame excel.

[hypervalent_iodine]

So far as I know, there is no order of preference for division and multiplication and in situations as above, you have to do the operation from left to right (making the answer 9).

 

It's also worth noting that this question brings about a rather tired debate, for which there have already been a number of threads.

[insane_alien]

this is why i hate division represented by a single line and why i always put brackets around what i'm dividing by (even if they aren't needed). If we could have a multiple line input like latex then that would solve all these problems.

[Vastor]

So far as I know, there is no order of preference for division and multiplication and in situations as above, you have to do the operation from left to right (making the answer 9).

 

It's also worth noting that this question brings about a rather tired debate, for which there have already been a number of threads.

 

not looking for much discussion about the order itself, but seriously, same company put two different answer(different order of calculation) on their calculator?

 

anyway, we all know that it was meant to be from left to right, right? never thought this kind of simple algebra would end up to be so complicated

[D H]

First one is correct. 1+2 in brackets give 3, and then multiplication before division. The right calculator is a straight-on calculator and would be wrong.

 

The first one is incorrect. For some unknown reason, calculator developers back in the late 1990s came up with their own precedence rules regarding implied multiplication. After having been met with criticism from scientists, engineers, mathematicians, and educators, most have since switched to using the standard precedence rules.

[hypervalent_iodine]

I only brought it up on account of Fuzzwood's comments, which suggested that 9 was an incorrect answer. It is definitely strange that a calculator would give an answer of 1 to that question.

 

Edit: looks like there's an explanation to it after all. I don't think I used calculators much in the 1990's on account of the fact that I was only just learning multiplication and division with 3 digit numbers

[DrRocket]

The only hard and fast rule in mathematics is that one must be clear.

 

The question is predicated on a potentially ambiguous mathematical sentence.

 

It is not a matter of what is "right". It is a matter of writing and expression that is easily understood.

 

It does not matter what convention you were taught in kindergarten. When in doubt go the extra inch to make yourself clear.

[Schrödinger's hat]

Also, neither calculator is wrong. Both are internally consistent, they are just following different conventions. You will likely find that both calculators act like the one on the right if you use the * or [math]\times[/math] button. 2*(1+2) instead of leaving it implicit 2(1+2).

The lessons we can learn from this are:

1) A world with many different conventions can be confusing.

2) Make yourself clear. When there are multiple conventions around you have to go the extra mile to avoid ambiguity -- as DrRocket said.

3) If you are going to use a tool, learn how it works.

[The Observer]

Its the like joke about clubbing baby seals. Neither interpretation is wrong, its just a poorly written sentence!

[Vastor]

ahah!

 

now I remember what to reply about the real problem, well I'm talking about the respond from the commenter of the pic itself

 

what I see is that they(most if not all) interpret it as:-

 

6 / 2(1+2)

 

but, they say "solve bracket first", make it

 

6 / 6

 

which is somehow ridiculous, at first I laugh how this poorly calculated, then there so many people supported it which either

 

a. my algebra still sucks.

 

b. their algebra(who telling "solve bracket first") are the one who sucks.

 

 

 

what I understand, solving "inside the bracket" =/= "outside the bracket", where when "outside the bracket", it just mean to be multiplication/division.