THE BIGGEST MISTAKES
STUDENTS MAKE IN
MATHEMATICS EXAMS
NOT READING THE QUESTION PROPERLY
Exam pressure creates tunnel vision. A student sees the word "calculate" and immediately starts working — without reading what exactly needs to be calculated, what information is given, and what format the answer must be in. This is especially common in the first 20 minutes of the paper when anxiety is highest.
A student who calculates the area of a shape when the question asked for the perimeter scores zero — even if the calculation itself is perfectly correct. A student who leaves an answer in cm² when the question says "give your answer in m²" loses the final answer mark. These are avoidable losses on questions the student actually knew how to do.
Read every question twice before writing anything. On the first read, understand what is being asked. On the second read, identify every piece of information given. Underline or circle key words: calculate, simplify, determine, prove, give your answer in metres. Only then start working.
NOT SHOWING WORKING — WRITING ONLY THE ANSWER
Many students believe that in Mathematics, only the final answer matters. This belief comes from years of homework where the teacher checked answers in the back of the textbook. In an exam, that approach destroys marks.
In a 5-mark question, the mark allocation typically looks like this:
- 1 mark — correct formula or method identified
- 1 mark — correct substitution of values
- 1 mark — correct simplification
- 1 mark — correct answer
- 1 mark — correct units or rounding
Write every step, even the obvious ones. State the formula. Substitute values. Simplify line by line. The examiner marks what they can see. They cannot give you credit for working that exists only in your head.
POOR TIME MANAGEMENT — STUCK ON ONE QUESTION
Students feel that leaving a question unfinished is a failure. So they sit on a difficult question for 20, 30, sometimes 40 minutes — trying to force it — while easier questions at the end of the paper go unanswered. This is one of the most expensive habits in Mathematics exams.
A 3-hour Mathematics paper out of 150 marks gives you roughly 1.2 minutes per mark. A 5-mark question should take 6 minutes maximum. A student who spends 30 minutes on that question has used the time for 25 marks of other questions — questions they may well have answered correctly. The opportunity cost is enormous.
Before you start writing, divide your time. Calculate: total time ÷ total marks = minutes per mark. Write your start time on rough paper. If you exceed your time budget on any question — circle it, move on, and return to it at the end if time allows. Easy marks first. Hard marks after.
LEAVING QUESTIONS BLANK
When a student does not know how to answer a question, they skip it and move on. This feels logical in the moment — "I don't know this, so there's nothing I can write." But in South African Mathematics exams, this assumption is wrong and costly.
There is no negative marking in NSC, NCV or Nated Mathematics. A blank answer and a wrong answer both score zero. But a partially correct attempt — even a rough, incomplete one — can earn 1, 2 or 3 method marks depending on how much correct reasoning is shown. Students who leave questions blank forfeit marks they could have earned just by writing something relevant.
Never leave a question blank. Even if you cannot solve it fully, write down what you know: the relevant formula, the values from the question, the first step. In a question about compound interest, write A = P(1 + i)ⁿ and substitute what you can. That alone may earn a mark. Something is always better than nothing.
ROUNDING TOO EARLY IN A CALCULATION
Students are taught to round answers — and they do it correctly at the end. The problem is many students round intermediate values during a multi-step calculation. They get 12.6667 and round it to 12.67 before using it in the next step. By the time they reach the final answer, the accumulated rounding error produces a result that does not match the memorandum.
The final answer mark is lost — even though the method was completely correct. In Finance questions especially, where values compound across multiple steps, early rounding errors can make a correct method produce a wrong answer by several rands or even hundreds of rands.
Keep all decimal places on your calculator throughout the entire calculation. Use the ANS button to carry the full unrounded value into the next step. Only round the final answer, and round only to the number of decimal places the question specifies — usually 2 decimal places for money, or as instructed.
IGNORING UNITS OR FORGETTING TO CONVERT
Students focus so hard on getting the calculation right that they forget to check whether all values are in the same unit before calculating — and whether the answer needs to be converted into the unit the question specifies. This is most common in Measurement and Space & Shape questions.
A calculation done with mixed units (e.g. some values in cm and others in m) produces a wrong numerical answer even when the method is perfect. Equally, a correct answer written in cm² when the question asks for m² loses the final answer mark. These are pure marks lost to carelessness, not ignorance.
Before any Measurement or Geometry calculation, check every value's unit. Convert everything to the same unit before you substitute into the formula. Essential conversions to know:
- 1 m = 100 cm = 1 000 mm
- 1 m² = 10 000 cm²
- 1 m³ = 1 000 000 cm³ = 1 000 litres
- 1 litre = 1 000 ml = 1 000 cm³
STUDYING WHAT THEY ALREADY KNOW
Revising topics you are already good at feels productive — the work goes smoothly, you get answers right, you feel confident. It is psychologically rewarding. Tackling topics you struggle with feels frustrating and demoralising. So students naturally drift toward their strengths and avoid their weaknesses, especially under time pressure.
If you enter the exam scoring 90% on Functions but 20% on Finance and Measurement, no amount of additional Functions practice will raise your total mark significantly. Your existing weaknesses are where your next 20 marks are sitting. Ignoring them means those marks stay on the table permanently.
Build your revision plan from past paper errors — not from what feels comfortable. Write a past paper. Mark it. List every question you got wrong and the topic it came from. That list is your revision priority list. Spend 70% of your study time on the topics at the top of that list — the ones you failed most often. Spend 30% maintaining your strengths.
NOT PRACTISING WITH PAST PAPERS UNDER EXAM CONDITIONS
Students read through past papers, look at the solutions and convince themselves they understand the work. Reading a solution and being able to reproduce it independently under timed conditions are completely different skills. The exam does not ask you to read — it asks you to perform.
Students who only read past papers are constantly surprised in the exam room — by the pressure, by the time constraint, by seeing a familiar question type but not being able to execute it without their notes. The exam environment is a skill that must be trained, not assumed.
Write past papers exactly as you will write the real exam. Set a timer. Sit at a desk. No notes, no phone, no pausing. Use only what you will have in the real exam — your calculator and the formula sheet. Mark your paper strictly with the official memo. Every mark you lose is a topic to revisit before the next paper. Do this at least once a week in the 6 weeks before your exam.
Read every question twice before writing
Show all working — every step
Manage your time — 1.2 min per mark
Never leave a question blank
Round only at the final answer
Convert units before calculating
Study your weaknesses first
Write past papers under exam conditions
📚 PRACTICE WITH REAL PAST PAPERS
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