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 Post subject: Number machine from GL Assessment Test -5Posted: Mon Jun 11, 2012 10:18 pm

Joined: Mon Jun 11, 2012 9:31 pm
Posts: 5
Look at the number machine.
N ÷4 +1 x2 ?
Nilesh started with the number N. Which of these is the number that Nilesh ended up with?
a. N/8 +2
b. N/4 +2
c. N/2 +2
d. N/4 +1
e. N/2 +1

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 Post subject: Re: Number machine from GL Assessment Test -5Posted: Mon Jun 11, 2012 10:31 pm

Joined: Thu Dec 18, 2008 10:12 am
Posts: 3758
Location: Berkshire
You just need to slot in a number and trial and error is the thing.

First thing I did was pick the number 8 (as it is a multiple of 4)

8 divided by 4 is 2

2+1 =3

3 x 2 =6

6 is 4 +2

ie N/2 +2.

I wouldn't have gone any further......maybe there is a way to work it out exactly, but this way we got the right answer.

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 Post subject: Re: Number machine from GL Assessment Test -5Posted: Mon Jun 11, 2012 10:35 pm

Joined: Thu Jul 14, 2011 9:18 am
Posts: 306
I'm sure someone will be able to express the answer better than me, but here goes

+ 1 x 2 = 2 - so it must be answer a, b or c

N/4 x 2 = N/2 - so answer c

To prove it, say N=16

N/4 +1 x 2 = 10
and 16/2 +2 = 10

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 Post subject: Re: Number machine from GL Assessment Test -5Posted: Tue Jun 12, 2012 1:18 pm

Joined: Mon Jun 11, 2012 8:51 pm
Posts: 27
I hope I am correct but I disagree with the answer given.
Surely N/4 + 1 X 2 is N/4 + 2, due to BIDMAS, which says we do multiplication and division before adding. To get N/2 + 2, the question would have needed to be
(N/4 + 1) x 2.

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 Post subject: Re: Number machine from GL Assessment Test -5Posted: Tue Jun 12, 2012 1:35 pm

Joined: Mon Jun 11, 2012 8:51 pm
Posts: 27
Sorry, I am wrong!! If this was a simlifying question I would be OK BUT with a number machine you simply go through in order!!
I really must learn to read the question!!

PS In case you haven't guessed I am new to this, and quickly becoming addicted.

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 Post subject: Re: Number machine from GL Assessment Test -5Posted: Tue Jun 12, 2012 2:12 pm

Joined: Tue Oct 04, 2011 8:44 am
Posts: 1390
surreymummy wrote:
I hope I am correct but I disagree with the answer given.
Surely N/4 + 1 X 2 is N/4 + 2, due to BIDMAS, which says we do multiplication and division before adding. To get N/2 + 2, the question would have needed to be
(N/4 + 1) x 2.

you have to be very careful with BIDMAS - or BODMAS as we used to call it - as I believe a lot of the questions should just be answered left to right and BODMAS ignored. I am not sure if it depends on the exam provider

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 Post subject: Re: Number machine from GL Assessment Test -5Posted: Tue Jun 12, 2012 4:47 pm

Joined: Sat Feb 13, 2010 11:02 pm
Posts: 420

you have to be very careful with BIDMAS - or BODMAS as we used to call it - as I believe a lot of the questions should just be answered left to right and BODMAS ignored. I am not sure if it depends on the exam provider

I totally disagree with this statement. I believe BODMAS should always be followed

As the original question is a number machine and so has to be done left to right,

Then mathematically it is

n/4
n/4+1
(n/4+1)*2

So if you expand the brackets it is

(n/4)*2+(1)*2
which gives you
n/2+2

PS please feel free to totally disagree with me, I am a DIY mum (going through it second time round) and not a tutor. (I just have very strong views about maths )

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 Post subject: Re: Number machine from GL Assessment Test -5Posted: Tue Jun 12, 2012 5:45 pm

Joined: Tue Jun 02, 2009 9:28 pm
Posts: 2439
I automatically used BODMAS as well and got the same answer as 999.

(I once nearly wrote to a kids comic because there was a sum on their fun page, and if you completed the sum using the BODMAS rules, they gave the wrong answer.)

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 Post subject: Re: Number machine from GL Assessment Test -5Posted: Tue Jun 12, 2012 7:28 pm

Joined: Thu Jul 14, 2011 9:18 am
Posts: 306
Just out of interest does that make my answer wrong? I don't know BODMAS (before my time?) and just worked it out

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 Post subject: Re: Number machine from GL Assessment Test -5Posted: Tue Jun 12, 2012 7:36 pm

Joined: Tue Oct 04, 2011 8:44 am
Posts: 1390
There certainly are practice papers floating around where it is left to right rather than Bodmas

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