The Most Common IGCSE Add Math Exam Mistakes (and Fixes)

Cambridge publishes examiner reports after every session, and reading several years of 0606 reports reveals something deflating and hopeful at once: candidates lose marks to the same short list of errors, every session, across the world. Deflating because the list never shrinks; hopeful because a known list is a fixable list.

1. Working done mentally, marks lost silently

The most-reported issue in 0606. Steps done in the head leave nothing for the examiner to award, and most marks in this subject are method marks. Fix: the one-step-per-line rule, with the general formula stated before substitution. It feels slower; it’s typically worth a grade.

2. Degrees when the question is in radians (and vice versa)

A trig equation with range $0 \le x \le 2\pi$ answered in degrees, or arc length s = rθ computed with $\theta$ in degrees. Fix: before touching any trig or circular-measure question, circle the range/units in the question. Ten seconds; recurring marks.

3. The dropped +c

Indefinite integration without the constant, the most predictable lost accuracy mark in the syllabus, and in kinematics it cascades: no constant means no initial-condition equation, which sinks the whole part. Fix: write +c in the same pen stroke as the integral, before simplifying anything (integration technique).

4. Invalid solutions left standing

The quadratic gives $x = 3$ and $x = -2$, but $x$ is a length; the trig equation yields a value outside the range; the log equation produces an argument $\le 0$. Leaving the impossible solution unrejected costs the final mark. Fix: after solving anything, one written sentence: ”$x = -2$ rejected since …”. The sentence itself is often the mark.

5. Rounding too early

Intermediate values rounded to 3 s.f., then used downstream, final answer drifts off the mark scheme’s tolerance. Fix: exact values (surds, fractions, $\pi$) until the final line on Paper 1; full calculator precision carried through on Paper 2, rounding once at the end.

6. “Hence” ignored

Part (ii) solved from scratch when it said hence, the mark scheme was written for the route through part (i). Fix: treat every “hence” as a hyperlink to the previous part; if your solution doesn’t use it, you’ve missed the intended door (command words).

7. Dividing away solutions in trig equations

$\sin x \cos x = \cos x \to$ divide by $\cos x \to$ the $\cos x = 0$ solutions vanish. Fix: never divide by an expression that can be zero; move everything to one side and factorise (trig technique).

8. Quotient/chain rule sign and bracket slips

$u'v - uv'$ flipped; the $\times 6x$ forgotten after differentiating $(3x^2 - 5)^4$. Fix: the written $u$, $u'$, $v$, $v'$ setup line, it slows the hand just enough to stop the slip, and earns the method mark anyway (differentiation technique).

9. Sketch questions answered without labels

A correct curve shape with unlabelled intercepts and turning points scores a fraction of the B marks. Fix: sketch = shape + labelled features. Say the coordinates out loud as you write them.

10. Time spent proving the unprovable

Ten minutes on a stuck 3-mark part while two accessible questions wait unread. Fix: the 1.5-minutes-per-mark rule from the exam format guide, flag, move, return.

Turning the list into marks

Generic “be careful” advice changes nothing. What works is an error log: every dropped practice-paper mark recorded by cause for three weeks (the marking routine). Most students find 80% of their losses come from two or three items on this page, and a targeted habit fixes each one in a fortnight.

This is also exactly what 1-to-1 marking feedback accelerates: Teacher Rig reads students’ scripts the way examiners do and runs the error log for them, week by week. The first session is a free 1-hour trial, message us on WhatsApp.