The on-screen calculator feels like a safety net, and that is exactly why it costs people marks. Reached for on every question, it quietly drains your time and introduces mistakes that mental maths never would. Used with discipline, it is a precision tool for the handful of questions that truly need it.
When the calculator actually wins
Reach for it when the numbers are genuinely ugly: long multi-digit multiplication or division, several decimal places, or a chain of operations where one slip throws everything off. Multiplying 487 by 36, or dividing 1,549.82 by an awkward rate, is a calculator job. Finding 20% of 300, or a quarter of 80, is not. The test is simple — if you can see the answer forming in your head, do not touch the keypad.
When mental maths wins instead
Clean percentages, simple fractions, rounding-friendly numbers and quick estimates are all faster in your head — and when the answer options are spread far apart, an estimate is often all you need to choose. Every time you skip the calculator on one of these, you save several seconds and remove a chance to mistype. Across 36 questions, that is the difference between finishing comfortably and running out of time.
Use the number pad, not the mouse
Enter numbers with the keyboard's number pad rather than clicking each digit with the mouse — it is far quicker and you keep your eyes on the screen. Practice this from day one so it is automatic on exam day. Clicking digits one by one with a mouse is one of the most common self-inflicted time leaks in the whole section.
Avoiding mis-clicks
Exam keyboards are not always responsive, so press each key firmly and deliberately rather than hammering them. Speed in QR is not about frantic typing; it is about entering the right keys, in the right order, first time. A single dropped digit or a misplaced decimal point gives you a confidently wrong answer that looks plausible, which is worse than no answer at all. Steady and accurate beats fast and sloppy.
The hidden time cost
The real cost of the calculator is not the typing — it is the switch. Moving your attention from the question to the keypad, entering the sum, then reading the result back and re-orienting all takes seconds you rarely notice individually but that add up sharply over a section. Treat each use as a small tax. If a quick mental estimate or a percentage-ladder step would do, the tax is not worth paying.
Build the instinct in practice
Knowing when to use the calculator is a skill, not a rule you can simply read. Train it by doing focused sets where the calculator is banned, forcing you to find the mental route, and other sets where you deliberately use it well. Over time you stop deciding consciously and just know, the moment you read a question, whether this one is a head job or a keypad job.