@biscuitwithmorecallories AKA chocolatehobnob: no worries mate!
@others
I would approach that question using approximations too, however if the answers were too close together i would use the pencil and paper provided.
Not all of the questions are hard and take their full share of the time. Working quickly is key to "banking" some time for harder questions.
I found the 3 and 60 times tables came into use a lot, so either get good at them, or spend some time at the start writing them out.. careful doing that though... as that's using time before you've banked any! better to answer all the questions, even with wind guesses if necessary..
(Note, that blind guessing wasn't my tactic... )