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Posted (edited)

Someone's been facebooking.

It depends on what comes after the brackets, multiply or divide. I was taught brackets, multiply and then divide.

 

In this case division comes first, when you have multiple groups of like operations (ie division and multiplication, addition and subraction), you work left-to-right.

 

So inside the brackets first -> (2+1)=3

This gives -> 6/2*3

 

Doing division first gives you -> 6/2=3

Then multiplying -> 3*3=9

 

The reason a lot of people get one is that they interpret the equation as 6/(2*(2+1)) - there is also some confusion as particular calculators treat a slash (/) as different to a division sign (which doesn't appear on normal computer keyboards)

Edited by Hiro Protagonist
Posted (edited)

interestingly if i put that equation into my scientific calculator (casio FX-82) as it is (using the fraction function for the slash) it gives an answer of 9.

 

If i replace the slash with a divide command, it gives an answer of 3.

 

Seems, like hiro mentioned, the calculator treats the divide differently than the fraction button in tems of order of doing things.

 

Seems as soon as the fx-82 sees a slash it treats the numbers either side as "number". in this case 6/2 = 3

Edited by ke70dave
Posted

Someone's been facebooking.

It depends on what comes after the brackets, multiply or divide. I was taught brackets, multiply and then divide.

I found it on 4chan, then lol'd for half an hour at the replies of everyone trolling.

 

Dave my Casio FX-82 gives 1 using the divide function. and 9 using the fraction function.

I would say the answer is 1.

I would treat the 2 outside the bracket as a coefficient, ie 2(2+1) = 2*2 + 2*1 = 6

Posted (edited)

I thought in algebra you assumed the multiply if its phrased like that in brackets and not expressed above or below a line or with an addition or subtraction mark. Therefore I get 9.

 

Brackets first, so 3 in there.

 

Then do the 6/2=3.

 

So 3(3)=9 does it not? Or is it supposed to be an unsolvable thing? I thought you just had to make assumptions to solve anything in mathematics? hah.

Edited by LittleRedSpirit
Posted

I think it depends on how its being presented?

 

if its presented as it would seem-

 

6

OVER

2(2+1)

 

So using the slash as an indicator of a fraction, rather than symbolising division

 

Then you get 6/6=1?

 

 

Posted

if its presented as it would seem-

 

6

OVER

2(2+1)

 

If you try to represent this in LaTeX you end up with this:

\frac {6} {2(2+1)}

 

frac2.gif

 

which AFAIK is like: (6)/(2(2+1))

 

If you write it as this:

\frac 6 2(2+1)

 

LaTeX gives you this:

frac3.gif

 

 

C and its derivative languages (Java, Python, PHP etc) will work it out (with a multiplication added) to be 9. To get 1 you have to start piling on brackets to force the order of operations to change.

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