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 Post subject: Help please
PostPosted: Tue Aug 13, 2019 5:52 pm 
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Joined: Tue Aug 13, 2019 5:33 pm
Posts: 2
Hello all,

I will appreciate if someone can help me regarding the following question. This is from CSSE 2017 entry Maths paper.

Q. Two square numbers have a difference of 33. Identify the two missing numbers that complete this calculations.
square(A) - square(B) = 33
fill in the two empty boxes to show our answer:
square(__) - square(__) = 33

My son gave us the following answer
square(17) - square(16) = 33

But the answer given at the end of the CSSE paper is as below -
square(7) - square(4) = 33

As you can see both the answers are correct. I just wanted check how would the checker treat this, if there are multiple answers possible and some of these are not mentioned on the answer sheet?


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 Post subject: Re: Help please
PostPosted: Wed Aug 14, 2019 9:13 am 
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Joined: Wed May 09, 2007 2:09 pm
Posts: 1198
Location: Solihull, West Midlands
This is a case where those setting the exam have not been careful enough - clearly there are two possible answers but they weren't expecting 10-year olds to know any square numbers other than 1-12, and were presumably expecting them to discover the answer by trial and error.

Well done to your son - has he spotted the pattern that pairs of adjacent square numbers always differ by successive odd numbers? He will go far with that kind of mathematical insight - a useful lesson that sometimes there is more than one "right" answer


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 Post subject: Re: Help please
PostPosted: Wed Aug 14, 2019 9:59 pm 
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Joined: Tue Aug 13, 2019 5:33 pm
Posts: 2
Many thanks for your kind reply


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 Post subject: Re: Help please
PostPosted: Thu Aug 15, 2019 6:03 pm 
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Joined: Tue May 22, 2018 7:23 am
Posts: 104
solimum wrote:
This is a case where those setting the exam have not been careful enough - clearly there are two possible answers but they weren't expecting 10-year olds to know any square numbers other than 1-12, and were presumably expecting them to discover the answer by trial and error.

Well done to your son - has he spotted the pattern that pairs of adjacent square numbers always differ by successive odd numbers? He will go far with that kind of mathematical insight - a useful lesson that sometimes there is more than one "right" answer


You've hit the nail on the head there. Knowledge of square numbers up to 12 should be taken as a given at 11+ level. Going on speed of calculations, trial and improvement within numbers 1-12 is what's required here.


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