By which is meant: knowledge of multiplication tables, of squares, cubes and other powers, lots of other multiplication skills so that many primes can be recognised from familiarity. Particularly the use of some algebraic techniques to render some arithmetic easier. Also, the use of several skills to check an answer.

One of the fundamental skills to pick up in year 8 is the automatic checking of an answer for sense. Is your answer the right size? Is it in sensible units? Is the precision appropriate? Is it the right sort of answer? (maybe you can tell whether it should be even, or prime, or end in a particular digit, ...)

 However, © David Scoins 2017