The Most Common Careless Errors in IGCSE Maths (and How to Fix Them)

Careless Errors: The Recoverable Mark Loss

In every IGCSE maths past paper Teacher Rig reviews, 15–25% of mark losses come from careless errors — mistakes that have nothing to do with topic knowledge. These are recoverable marks.

The Most Common Careless Errors

1. Misreading the question Examples: “find the exact value” answered with a decimal; “give your answer to 2 decimal places” answered to 3; “find angle ABC” answered with the supplement.

Fix: Read every question twice. After answering, re-read the final question sentence to check the format of the answer required.

2. Arithmetic errors in non-calculator working Multiplying single-digit numbers incorrectly (7×8=54 instead of 56) or adding incorrectly in column arithmetic.

Fix: Write neatly and check arithmetic by reverse-checking: if 7×8=56, does 56÷7=8? This takes 5 seconds per calculation.

3. Sign errors in algebra Distributing a negative sign: -(3x-4) written as -3x-4 instead of -3x+4.

Fix: Slow down on every expansion involving a negative. Highlight or circle the negative sign before expanding.

4. Forgetting units Writing “38” instead of “38°” for an angle, or “24” instead of “24 cm²” for an area.

Fix: For every measurement answer, check: does this need a unit? Write it before finalising the answer.

5. Calculator mode errors Degrees vs radians (see calculator tips guide).

6. Not reading “give the exact value” “Exact value” means leave the answer as a fraction, surd, or exact decimal — not a rounded approximation.

Fix: Circle “exact” every time it appears in a question.

7. Omitting negative solutions Quadratic equations solved by formula give two solutions. Students who find one solution and stop lose marks.

Fix: After solving any quadratic, ask: does this equation have two solutions? Write both.

How Many Marks Are You Losing?

In Teacher Rig’s experience, a student losing 15–20 marks to careless errors per full paper can recover 10–15 of those marks through habit change alone — without learning any new content. This is often the single highest-return intervention available.

Book a free trial — Teacher Rig identifies your child’s specific careless error patterns in the first diagnostic session.