A little bit of intuition and then a little bit of playing around with numbers...

I cheated a little and made a leap in assuming that one of the fractions would be simple given the problem is for 11 year olds and so tried 1/2 firstt. I then needed to find away of creating 0.5 with the other digits. So the denominator and numerator can only start with the following options:

9/4, 8/4, 7/3, 6/3, because the 2 and 1 have already been used.

Then it was just a case of playing around with the remaining digits so that the bottom number is twice that of the top number.

It wouldn't surprise me if they have been taught a method that escapes me, but then I am a physicist and not a pure mathematician! Funnily enough you do find that there are some problems that kids can do that experienced mathematicians can't do because they simply haven't done those kinds of problems for a long time.

Posted By: Rob NCFC, Jan 15, 17:05:02