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Maths GCSE exams are all about accuracy, logic, and clear working. But even the most capable students can lose marks to simple, avoidable mistakes—especially under time pressure. In this post, we’ll look at the most frequent errors students make and how you can avoid them to secure the marks you deserve.

1. Not Showing Working

The Mistake: Giving a final answer with no method shown—even when it’s correct—can cost you marks, especially on multi-step problems.

How to Fix It: Always write out each step of your calculation. Even if your final answer is wrong, you can still get method marks if your working shows the correct process.

2. Calculator Over-Reliance (or Underuse)

The Mistake: In calculator papers, students sometimes do basic steps in their heads and make errors, or use the calculator incorrectly.

How to Fix It: Use your calculator wisely—check complex calculations, brackets, and inputs carefully. And in non-calculator papers, practice mental and written arithmetic regularly to build speed and accuracy.

3. Poor Time Management

The Mistake: Spending too long on one difficult question and running out of time for others.

How to Fix It: Don’t get stuck. If a question is taking too long, move on and come back to it later if time allows. Keep an eye on the clock and aim to leave 5–10 minutes at the end for review.

4. Forgetting Units and Labels

The Mistake: Giving an answer with no units (e.g. cm, m², £), which often results in lost marks.

How to Fix It: Always check if the question requires a unit, especially in geometry, measure, and money questions. Make this a habit in practice so it becomes automatic.

5. Misreading the Question

The Mistake: Answering a different question than the one asked—e.g., finding the radius instead of the diameter.

How to Fix It: Underline or highlight key information in the question. Pause and ask yourself: What is this question actually asking me to find?

6. Sign and Direction Errors

The Mistake: Mixing up positive and negative numbers, or giving the wrong direction (e.g., North instead of South-East).

How to Fix It: Be extra careful with minus signs and vector directions. Draw diagrams when appropriate and double-check your final answer makes logical sense.

7. Not Checking Answers

The Mistake: Finishing early and not using the time to check, missing obvious mistakes like 7 × 6 = 36.

How to Fix It: Always use leftover time to double-check answers, especially for questions with high mark values. Recalculate or estimate to verify your result.

8. Leaving Blanks

The Mistake: Not attempting a question at all, especially on tricky algebra, probability or geometry questions.

How to Fix It: Always try something—write down what you know. You might earn method marks even if you don’t reach the final answer.

Final Tips

  • Practice under timed conditions.
  • Use past papers and mark schemes to understand what examiners expect.
  • Get into the habit of writing clearly and logically.
  • Don’t panic—use your exam techniques.

Success in Maths GCSE isn’t just about knowledge—it’s about approach. By being aware of these common mistakes and practicing smart strategies, you can avoid unnecessary errors and pick up more marks.