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 Post subject: maths question
PostPosted: Thu Sep 21, 2017 1:20 pm 
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Joined: Tue Jul 21, 2009 9:56 pm
Posts: 8922
What's the answer to 6 div 2(2+1) ?

div = division sign - the type with a short line with a dot above and below it, sorry not got one on this keyboard


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 Post subject: Re: maths question
PostPosted: Thu Sep 21, 2017 3:39 pm 
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Joined: Wed Sep 02, 2015 9:56 am
Posts: 283
BIDMAS so...
6 / 2 X (2 + 1) =
6 / 2 X 3 =
3 X 3 =
9


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 Post subject: Re: maths question
PostPosted: Thu Sep 21, 2017 3:45 pm 
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Joined: Fri Mar 10, 2017 4:06 pm
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I would also say the answer is 9. Based on BODMAS going left to right.
i.e. 6 divided by 2 multiplied by 3.

But then I could understand if others thought the answer was 1.

Does the lack of a multiplication sign between the 2 and the (2+1) mean that the multiplication should be performed before the division or does it make no difference. Does the type of division sign used matter?

Hopefully Guest55 will be along soon to provide the definitive answer. :)


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 Post subject: Re: maths question
PostPosted: Thu Sep 21, 2017 4:20 pm 
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Joined: Wed Sep 21, 2011 10:30 am
Posts: 802
I would say 9 too using BODMAS


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 Post subject: Re: maths question
PostPosted: Fri Sep 22, 2017 12:04 pm 
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Joined: Wed Sep 02, 2015 9:56 am
Posts: 283
Surferfish wrote:
Does the lack of a multiplication sign between the 2 and the (2+1) mean that the multiplication should be performed before the division or does it make no difference.

There is some debate in maths circles around this. Given, this is the 11+ then I think following BIDMAS (or BODMAS) and counting the implicit multiplication as a explicit multiplication is the best approach. Interested in Guest55's thoughts though.

Surferfish wrote:
Does the type of division sign used matter?

Only when a fraction is used which is not the case here. You have to apply BIDMAS to the numerator and the denominator separately before simplifying the fraction.

OP - What was the answer given?


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 Post subject: Re: maths question
PostPosted: Fri Sep 22, 2017 12:18 pm 
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Joined: Sat Oct 01, 2016 5:02 pm
Posts: 1172
I'm confused. I thought BIDMAS means that you do the brackets first (the B of BIDMAS). 2 + 1 = 3. The 3 is then multiplied by 2 to get 6, then 6 is divided by 6 to get 1.

But it's been a long time since I was at school...


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 Post subject: Re: maths question
PostPosted: Fri Sep 22, 2017 1:11 pm 
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Joined: Thu Dec 11, 2008 9:42 pm
Posts: 919
I thought 1 also


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 Post subject: Re: maths question
PostPosted: Fri Sep 22, 2017 2:30 pm 
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Joined: Fri Mar 10, 2017 4:06 pm
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streathammum wrote:
I'm confused. I thought BIDMAS means that you do the brackets first (the B of BIDMAS). 2 + 1 = 3. The 3 is then multiplied by 2 to get 6, then 6 is divided by 6 to get 1.

But it's been a long time since I was at school...


Yes, BIDMAS means that you always do what's INSIDE the brackets first. i.e. (2 +1) = 3.

That gives you: 6 div 2(3).

The debate is about what you do next. The division or multiplication and whether lack of a multiplication sign trumps 'left to right' rule.

(I doubt this would be an 11plus question BTW.)


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 Post subject: Re: maths question
PostPosted: Sat Sep 23, 2017 5:58 am 
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Joined: Tue Mar 03, 2015 7:39 am
Posts: 32
Question is 6 / 2(2+1) to be written as
6
---------
2(2+1)

and not

6
------ x (2+1)
2

When you have 2(2+1), this means the expression was 4+2 inside the bracket, and one of the factors 2 is common and taken outside the bracket. When you solve for a bracket, you have to solve 2(2+1) in its entirety and not just the 2+1 which is inside the bracket. Answer should be 1 and not 9


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 Post subject: Re: maths question
PostPosted: Sat Sep 23, 2017 11:30 am 
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Joined: Mon Dec 24, 2018 3:27 pm
Posts: 47
This problem is debated on so many social media sites and in so many country. Admittedly I got into one these debate.


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