My son likes maths, is in Y6 and regarded as very able. However while he's obviously very good at it, he doesn't do perfectly. E.g., in the Primary Maths Challenge, he got 21/25, where 23 was the bonus round mark. I had him do a couple of the PMC bonus round papers, and he got 19/25 on 2012's paper (which would have been bronze out of the bonus round entrants), and 20/25 on 2011 (silver).
Obviously quite creditable, but he's clearly not the highest echelon. Is it possible to get there? Or is he just a case that he's a three-sigma student, but never six-sigma, so to speak?