Revision Tips for GCSE/IGCSE Maths Exams 8: Exam technique 3: Some common mistakes to watch out for


This is the 8th in a new series of blogs for students revising GCSE Maths, or IGCSE Maths in preparation for the AQA GCSE Mathematics or Edexcel IGCSE Mathematics exams.

Some common mistakes to watch out for

It is all too easy to make silly mistakes during your GCSE/IGCSE maths exam. Obviously the fewer you make the better your result will be so here are some common ones to watch out for:

Check +/- signs

This is particularly true when solving equations. It is very easy to “lose” a minus sign by mistake part way through a solution so always check  through your work afterwards.

Read ratio questions VERY carefully

Some ratio questions deal with the whole ratio and some deal with just one part so make sure you are clear which type you are dealing with.

Know your fraction, decimal and percentage equivalents

One of the most common mistakes quoted by examiners is that of taking ⅛ to be equal to 30%

Give common sense answers

Make sure that any answers you give are sensible. Probabilities have to lie between 0 and 1 and they must  be positive – any answer that is bigger than 1 or negative must be wrong.  The mean of a list of numbers cannot be larger or smaller than all of the numbers in the list.  When finding the missing side of a right angled triangle using either Pythagoras’ Rule or trigonometry the shorter sides cannot be longer than the hypotenuse.

Check your calculator settings

For trigonometry at GCSE level (Higher papers only) your calculator should be in the “degrees” setting. This is usually denoted by a small D in a box – if yours has an R or a G instead you need to reset it.

There may be a clue in the question

A question which asks you to solve a quadratic equation correct to 3 significant figures (Higher paper only) is unlikely to be easily factorised so use the formula.

Use tracing paper

Tracing paper is allowed in all GCSE Maths exams so use it to check questions on transformations, especially rotations and reflections as it is very easy to get these wrong if you do them by sight.

In general:

Write as clearly as you can, reread each question and double check every answer if you have time!

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