How to stop making silly mistakes in GCSE Maths
Everyone makes silly mistakes. You know how to do the question, you get it wrong, and then you see it as soon as the paper's handed in. It's one of the most annoying things in the whole exam, and it's also one of the most fixable.
A silly mistake isn't a sign you're bad at Maths. It's a habit problem, and habits can change. Here are seven that work.
1. Sort your mistakes first
Before you change anything, find out which kind you make. After each past paper, look at every lost mark and ask whether it was a slip, a near miss or a gap. Slips are the silly ones: arithmetic errors, a misread question, a missing minus sign, no units.
Write them in a notebook with the topic next to each. After two or three papers you'll see the same ones coming back. A mistake you can name is a mistake you can stop.
2. Read every question twice
The first time, read to understand the question. The second time, read with a pen and underline what it's asking for and the numbers you've been given.
This catches a lot: "work out the perimeter" when you found the area, "give your answer in pounds" when the figures are in pence, "how many more" instead of "how many". It takes ten seconds and saves marks all through the paper.
3. Show your working, every time
Write each step on its own line, even the ones that feel obvious. This stops mistakes in the first place, because you can see what you're doing. If you do slip, the mark scheme gives method marks for correct working, so you can still earn marks with a wrong answer. With no working, there's nothing to give.
Here's a short video on spotting one of the most common slips with percentages:
4. Watch the signs, brackets and units
Three things cause many silly mistakes:
- Negatives. When you subtract a negative or multiply two negatives, slow down and write the sign out.
- Brackets. Expand or square a bracket on its own line, not in your head.
- Units. Write them next to every number. Convert to the same unit before you calculate.
5. Use your calculator to check, not only to calculate
On Papers 2 and 3 you can use a calculator. After you've worked an answer out, ask whether it makes sense. A probability above 1, a negative length or an area bigger than the whole field is a warning sign. Do a rough estimate in your head first, then compare. Remember that Paper 1 doesn't allow a calculator, so practise checking by hand too. My calculator tips post has more on this.
6. Pace yourself
Each paper is 80 marks in 1 hour 30 minutes. That's a little over a minute a mark. If you rush, you make silly mistakes. If you spend ten minutes on a three-mark question, you rush the end. If you're stuck, write down what you know, move on and come back at the end.
7. Keep the last five minutes for a checklist
Don't spend the final minutes staring at the clock. Run through the same short list every time:
- Did I answer every question? Check for blanks, and put something down for each one.
- Did I answer what was asked? Look back at the last line of the longer questions.
- Are my units and rounding right? Check the decimal places or significant figures asked for.
- Do the answers make sense? Look for anything impossible.
- Redo one question. Pick one you were least sure of and do it again a different way.
Practise the checklist in your past papers, so it's automatic when it counts. Here's how I'd use every paper you do:
Questions people also ask
Why do I make silly mistakes in Maths?
Usually it's rushing, skipping working, or misreading the question, not a lack of knowledge. Under pressure we go on autopilot. Writing each step down and reading every question twice slows you down just enough to catch them.
How do I stop making silly mistakes in a Maths exam?
Build the habits into your practice, not only the exam. Mark your past papers, write down every slip, and use the same checklist at the end each time. The more automatic it is, the less you have to remember on the day.
Do silly mistakes lose a lot of marks?
They can add up, because a single slip can cost a mark or more on several questions. They are also the marks you're most able to win back, because you already know how to do the Maths.