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The clock has started and the student next to you is already filling their rough sheet with formulas. Should you? A short, planned formula dump can help. A long, anxious one costs you marks. Here is how to tell the difference.
Does writing formulas at the start of an exam actually help?
The case for it comes from research on pressure and working memory. In a study of maths under pressure, Beilock and Carr (2005) found that performance pressure harms maths problem solving by using up working memory capacity. The damage was concentrated on the problems that demanded the most working memory, and it hit the students with the most working memory to lose. For background, see our explainer on Alan Baddeley's working memory model.
Writing things down is a form of cognitive offloading. Cognitive offloading is the use of a physical action to reduce the mental demand of a task, as defined in a review by Risko and Gilbert (2016). A formula on paper is one less thing you have to hold in your head while you work through a long problem.
Be honest about the limits. We found no study that tested a start-of-exam formula dump directly. The closest evidence is a warning: in an experiment with 54 undergraduates, Dickson and Miller (2005) found that crib cards students were allowed to bring into exams did not improve scores on either higher-order or lower-order questions, and did not reduce anxiety. A sheet only helps if you already know how to use what is on it.
Are you allowed to write on the rough sheet before you start?
Check the rules for your exam, because they differ, and read the latest advisory for your session. For JEE Main, the National Testing Agency's 2022 candidate advisory says blank A4 sheets for rough work are provided in the hall, you must write your name and roll number on each one, and you must drop them in the box before leaving. The same advisory bars you from carrying stationery or any printed or written material in, so everything on the sheet must come from memory.
CBSE board papers work differently. A 2025 CBSE Class 12 question paper (Q.P. Code 27), for example, states that the paper is handed out at 10.15 a.m. and candidates only read it until 10.30 a.m., without writing in the answer-book. Use those 15 minutes to decide what goes in your dump, then write it the moment writing time begins.
What should you write on your rough sheet?
Put something on the sheet only if it passes all three tests:
You have forgotten it, or mixed it up, in at least one mock test.
It is easy to confuse with something similar.
More than one question in the paper is likely to need it.
Leave out formulas you use every day, derivations and whole chapters. Here is a worked example for a JEE Main student whose mock tests showed sign and identity slips:
Lens: 1/v − 1/u = 1/f. Mirror: 1/v + 1/u = 1/f.
sin(A + B) = sin A cos B + cos A sin B, and cos(A + B) = cos A cos B − sin A sin B.
The two values of R this student keeps confusing, each written with its units.
One line on which way the sign convention runs, drawn as a small arrow.
Four lines, each there because a mock test showed it was weak. Our guide to using your mock test data shows how to find those weak spots.
If the same formula keeps slipping, it is often a gap in understanding rather than memory. The Fermi Concept Library has a lesson for every concept in physics, chemistry, biology and mathematics, so you can see where a formula comes from instead of memorising it cold.
How long should a formula dump take?
Aim for two to three minutes and no more than about eight lines. A CBSE paper allows 3 hours, according to the same question paper, so three minutes is a small price. Ten minutes of copying formulas you already know is not.
Rehearse it like any other skill:
Build your list from your last three mock tests.
Write it from memory, in the same order, at the start of your next two mocks.
Time yourself. Cut anything you never looked at again.
Freeze the list a week before the exam.
When should you skip it?
Skip it if your weak formulas are already automatic, or if the paper is mostly recall and theory with little calculation. Never stall on it: if one item will not come back, leave a blank line and start the paper.
If nerves are the bigger problem, a different kind of writing may suit you better. Our piece on writing about worries before a test covers what that research found. If exam stress feels heavy for weeks, talk to a parent, teacher or counsellor, or call Tele MANAS on 14416.
For your next mock, build your four to eight lines tonight and time the dump.
