The arithmetic nobody does
Marks per minute is the only quantity that matters, and it is wildly non-uniform within a question. The first 40% of the marks on a question typically take about 20% of the time — the definition, the setup, the obvious first steps. The last 20% of the marks take about half the time.
Which means: the fifteenth minute of question two is worth a fraction of the first minute of question five. If question five is blank, you have taken your most expensive marks and paid for them by forfeiting your cheapest ones. This single fact, internalised, is worth more than any other timing advice.
Set the budget before you write anything
- 1
Divide total minutes by total marks
A three-hour paper worth 100 marks is 1.8 minutes per mark. Round it: roughly two minutes a mark. Do this in the reading time, on the question paper.
- 2
Subtract a buffer of about 10%
Fifteen minutes on a three-hour paper, for reading, planning and the overrun that will happen. Budgeting to 100% guarantees a shortfall.
- 3
Write a finish time next to every question
Not a duration — a clock time. "Q3 by 10:42". Under pressure you will not do arithmetic reliably, and a duration requires arithmetic every time you check.
- 4
Decide the order now
Most papers don't require sequential answering. Starting with your strongest question banks marks early and settles the nerves; leaving the hardest until last means it can only eat the buffer, not another question.
- 5
Set a hard abandon rule and state it to yourself
"If I'm three minutes past a finish time, I stop mid-sentence and move on." Deciding this in advance is what makes it possible; in the moment, sunk cost wins every time.
The move-on rule
The commonest cause of an unfinished paper is a single question you were sure you could get. You're close, you've invested twelve minutes, one more idea will crack it — and this is a sunk-cost trap operating under stress, when your judgement about "nearly there" is at its least reliable.
- Leave it mid-sentence and return only if there's buffer left. Do not tidy up before moving on; that's more time spent on the expensive marks.
- Leave physical space — a half page — so returning is possible without cramming into a margin.
- Write down where you got stuck in three words. Coming back cold to an abandoned question otherwise costs two minutes of re-reading your own work.
- The answer often arrives while you write something else. This is real and is another argument for moving on rather than staring.
Where the time actually goes
| Time sink | Typical cost | Fix |
|---|---|---|
| Perfecting an answer that's already at full marks | 10–20 minutes per paper | Stop when you've hit the mark allocation. Extra prose earns nothing. |
| Re-reading the question repeatedly mid-answer | 5–10 minutes | Underline the instruction verb once at the start; don't re-derive it. |
| Redrawing a diagram neatly | 5–15 minutes | Label clearly, draw once. Neatness is not on the mark scheme. |
| Rewriting a crossed-out section | 5–10 minutes | One line through, keep going. Crossed-out work isn't marked and isn't penalised. |
| Deciding which optional question to answer | 3–8 minutes | Decide in reading time, commit, don't revisit. |
| Checking arithmetic you already checked | 5 minutes | One check, at the end, with the buffer — not three during. |
When you're already behind
Twenty minutes left, two questions to go. The instinct is to write a proper answer to one and leave the other blank. That's the wrong allocation almost every time.
- 1
Split the remaining time by the remaining marks
Not evenly by question. Ten minutes each if they're equal; skewed if they aren't.
- 2
Write in structured bullets, not prose
Markers award content, and a bulleted outline that hits six scheme points scores far more than two beautifully written paragraphs hitting three.
- 3
Lead with the conclusion or the answer
State the result first, then support. If you're cut off, the most valuable sentence has already been written.
- 4
For calculations, write the method even without the numbers
Method marks are usually available separately from the answer. "Apply conservation of momentum, then solve for v₂" earns marks that a blank page doesn't.
- 5
Never leave anything blank
A guess costs seconds and has non-zero expected value on almost every paper. A blank is a guaranteed zero.
Diagnose before you fix
"I ran out of time" has several distinct causes and they need different responses. Look at your last timed paper and work out which one is yours.
- Slow recall — you knew it but took a long time to retrieve it. This is a revision problem: your material isn't retrievable enough, and more retrieval practice fixes it.
- Over-answering — full marks reached and still writing. A discipline problem, fixed by writing finish times down.
- Getting stuck — one question ate everything. A move-on rule problem.
- Genuinely too slow at writing — worth raising with your institution; extra time is a standard adjustment where there's a documented need.
Categorising this properly is exactly the exercise a mock exam is for, and it's why the mock's mark distribution matters more than its score.