maths help!

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moose

maths help!

Post by moose »

In Athey maths Paper 2 :
8+6+7-2+9-1= ...
According to my knowledge of maths learned abroad it is 9.
I noticed that in my son's school they seem to ignore the basic maths rules, therefore according to what he would have learned in school the result would be 27.
There cannot be 2 different result of the same simple equasion for goodness sake!

I do not have the answer sheet re the above Athey' test therefore do not know what result is suggested by them . Could someone enlighten me please.
jah

Post by jah »

Problem as written, answer is 27.
moose

Post by moose »

That is not the right answer since you should do first what is in brackets, then multiplication, divisions, adding and subtracting. And in that order. Any other is not correct.
Anyone agrees with me?
KenR
Posts: 1506
Joined: Fri Mar 17, 2006 6:12 pm
Location: Birmingham

Post by KenR »

Jah,

Your answer is incorrect - the correct mathematical answer is 9. I agree with with Moose.

This type of issue came up last year and we had a long debate about it. The problem is that mathematically you should use BIDMAS to answer the question correctly from a mathermatical point of view - BUT childen are not taught BIDMAS as part of KS1 or KS2. So schools tell children to just work it out from left resulting in an incorrect answer.

I think we concluded that in an formal 11+ exam we would hope that the question would be unambiguous by the inclusion of brackets.

From a mathematical point of view 27 cannot be the answer.

Hope this helps
Catherine
Posts: 1348
Joined: Sun Dec 04, 2005 4:47 pm
Location: Berks,Bucks

Post by Catherine »

There is no bracket, division or multiplication in you equation.
You can do the additions and subtractions in any order, you will get 27!

Please explain, I don't see how you can possibly get 9...
moose

Post by moose »

Thank you! Will have to stick to what they teach in schools, though I think I will not resist temptation and explain to my son that it is not correct way of solving the problem.
Catherine
Posts: 1348
Joined: Sun Dec 04, 2005 4:47 pm
Location: Berks,Bucks

Post by Catherine »

moose, I think that we posted at the same time. I would really like someone to explain how the result of 9 can be obtained...
mum
Posts: 145
Joined: Tue Jan 16, 2007 9:49 am

Post by mum »

In Athey maths Paper 2 :
8+6+7-2+9-1= ...
I repeat as well, there is no bracket, division or multiplication in the above sum. The answer 27 is correct as its a simple addition & subtraction which can be done in any order..........
I do not agree with answer 9, unless there is some misprint......
mum
Heidi

Post by Heidi »

The answer, if followed step by step , (which it should in this case as there are no brackets), is of course 27.

If the two equations were treated separately then:
8+6+7 ( 21) - 2+9-1 (10)
21- 10 = 11

Sorry, I'm uncertain as to how moose got 9.
moose

Post by moose »

Catherine,
You need to add first, so let us put brackets around additions
(8+6+7)-(2+9)-1= 21-11-1=9
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