11 Plus Exams Forum

I am usually good at these and so is my son! But this one has me stumped,ideas anyone,it is probably very easy and I am missing the pattern.

8 (13) 11
6 (14) 10
3 (? ) 11

What is the missing ?? Answer given is 18???

(from Susan Daughtrey Further Practice Exercises page 31)

Thank you in advance!!

Gloucestermum

Take the small number from the larger number and then add ten.
ie 10 minus 6 = 4 (add ten =14) etc.

Thank you for that,it is easy when you know how!!!

Regards,Gloucestermum

Patricia has a tip for these bracket maths somewhere. Hopefully she'll drop in and post the link.##Basically many of the questions involve two operations. So always try

Operation 1 = + ,- ,X, or, / (divide) the outside nos ; then
operation 2 = +, -, X or / by an integer, or by either the left or right outside number

So if you are stumped always try each of the 4 possibles in operation 1, then ask yourself which operation 2 would you need to do to get to the middle number. Does it work for both examples. If yes you've got it.

So in the present case:
operation 1 = - (subtract the outside numbers - smallest from largest) then
operation 2 you can work out to be + an integer, in this case 10. It works for both so it must be right.

Genrally when you've done lots the anwsers leap out at you (honestly they do after enough practice) so you don't have to go through all the possible operations 1 and 2. But it is useful to have this as a technique to fall back on when you are stumped. My 10 year old got used to doing it, and in a set of 6 questions of this type, there was usually one tricky one he needed to use it for. Good luck. Hope this makes sense.

gloucestermum wrote:
8 (13) 11
6 (14) 10
3 (? ) 11

I agree with you... that is hard.

11 (13) 8
10 (14) 6
11 (? ) 3

seems much easier. It's actually a triple operation the first way around...

a ( -a+b+10 ) b

negation of a; addition of b; addition of constant

Dear Gloucester Mum

Four your information...

http://www.elevenplusexams.co.uk/forum/ ... .php?t=620

Patricia

Thank you Patricia much appreciated!!

Glosmum