The arithmetic is only half of a timed screen. The other half is strategy, and it is the half candidates neglect.
Find out the scoring rule
Before anything else. There are three regimes and they demand different behaviour:
- No penalty for wrong answers: never leave a blank. Guess everything you cannot solve.
- Penalty for wrong answers: a blind guess has negative expected value. Skip.
- Penalty, but you can eliminate options: guess only when you have narrowed enough to make the EV positive.
Candidates routinely guess on penalty-scored tests because a blank feels like failure. It is not - it is the correct play. See the probability OA explained.
Accuracy before speed
The instinct is to push pace until you are barely keeping up. That is backwards.
Build to a high accuracy rate at a comfortable pace, then compress. Speed acquired on top of a shaky base just produces fast errors, and on a penalty-scored test fast errors are worse than slow ones.
Track both numbers in practice: how many you got right, and how many you got right in time.
Do not sink time
The single most expensive mistake is spending 90 seconds on one question in a test averaging 8 seconds each. You lose the question and ten others.
Set a personal cutoff - roughly twice the average time per question - and move on when you hit it. Flag it and return if there is time.
The first questions matter more
Fumbling the first two or three questions costs disproportionately: it burns clock and it rattles you for the rest.
Warm up beforehand. Ten minutes of mental math before you sit down means you arrive at question one already at pace rather than accelerating into it.
Read the question
Misreading is a more common failure than not knowing. On a screen full of similar-looking items, "which is larger" and "which is smaller" alternate deliberately.
Managing nerves
Your arithmetic degrades under adrenaline. The countermeasures are boring and they work: sleep, warm up, and take the practice tests under realistic conditions so the real one is not the first time you have felt the clock.