**possible
related topics** calculations, equations

Learners might take issue with the calculation for 9, since π
is not *exactly* 3.14. Square brackets might be added to this one to
indicate rounding to the nearest integer.

They might also query the quadratic equation for 7, which
has two solutions. Adding ‘*x* > 0’ would do the trick here.

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© Colin Foster 2012, www.foster77.co.uk