Master speed calculation techniques for Quantitative Aptitude with fraction-percentage shortcuts, LCM methods, and formula tricks.
Quantitative Aptitude is often the most time-consuming section in banking exams. Long divisions, repeated percentages, and multi-step word problems eat into your 20 minutes faster than any other section. The good news: with the right tricks and mental math techniques, you can dramatically reduce your calculation time and improve accuracy at the same time. Before you start drilling, confirm the current exam pattern, sectional timing and number of questions in the quant section from the official website, because the tighter the sectional limit, the more aggressively you must lean on these shortcuts.
Speed is not about rushing. It is about removing wasted steps. A candidate who recognises a pattern solves in one line what a slower candidate solves in six. Across a full section of 35 questions, those saved lines add up to several extra attempts, and in a tight cut-off race three or four extra correct answers can be the difference between selection and a near miss. The tricks below are the ones that repay the most time per minute of practice.
These conversions appear repeatedly in Percentage, Profit & Loss, and SI/CI problems. Learn them like multiplication tables:
When a question asks for 14.28% of 4900, do not multiply; recognise the fraction and compute 4900/7 = 700 instantly. This single habit saves 15-20 seconds on every question in a DI set. The same logic works in reverse: if a value rises from 800 to 900, that is a 100/800 = 1/8 = 12.5% increase, read straight off the table with no division at all. Extend the list to their multiples too, so that 37.5% is instantly seen as 3/8 and 62.5% as 5/8.
For two successive percentage changes, use: Net% = a + b + ab/100. Example: a 20% increase followed by a 20% decrease gives 20 - 20 - 400/100 = -4%, a net 4% fall. The same formula handles discount-on-discount and population growth problems, eliminating the need for step-by-step calculation. Keep the signs strict: a decrease is a negative value, so a 10% rise followed by a 20% fall is 10 - 20 - 200/100 = -12%. Once this is automatic, most two-step percentage questions collapse into a single mental line.
Always convert Time & Work problems to LCM-based units instead of fractions. If A takes 10 days and B takes 15 days, take total work = LCM(10, 15) = 30 units. A does 3 units/day, B does 2 units/day; together they do 5 units/day, so the job takes 30/5 = 6 days. This integer-based approach is faster and far less error-prone than adding 1/10 and 1/15 under pressure. The exact same units trick powers Pipes and Cisterns and Time, Speed and Distance: fix the distance or the tank capacity as the LCM of the given numbers, and every rate becomes a clean whole number you can add and subtract in your head.
For partnership problems, remember one rule: the profit-sharing ratio equals investment multiplied by time for each partner. If A invests ₹5000 for 12 months and B invests ₹6000 for 10 months, the ratio is 60000 : 60000 = 1 : 1, no lengthy working needed. Similarly, when quantities are mixed or divided, write the ratio first and scale it, rather than computing absolute values at every step. In mixture and allegation questions, the criss-cross rule gives the required ratio directly, so you almost never need to set up an equation. Training yourself to think in ratios first keeps the numbers small and the arithmetic honest.
A large share of DI and simplification questions only need a close answer, not an exact one, because the options are spread far apart. Round 2987 to 3000 and 48.7% to 50% early, solve fast, then pick the nearest option. For squares near a base, use (a + b)squared = a squared + 2ab + b squared; 43 squared becomes 40 squared + 2×40×3 + 3 squared = 1600 + 240 + 9 = 1849 in one pass. Numbers ending in 5 are even easier: 65 squared is 6×7 followed by 25, which is 4225. These are small habits, but in a section built on repeated arithmetic they compound into real minutes saved.
Spend 10 focused minutes every day revising tables up to 25, squares up to 30, and cubes up to 15. Then apply them inside timed topic tests so the recall becomes automatic under exam pressure. Practice in a real exam interface, the way Quiz4Exam topic-wise and sectional tests present questions, so that on-screen calculation feels as natural as paper. A useful weekly drill: pick any 30 random calculations from old DI sets and race to finish them in 10 minutes; beat your own time every week and this section will stop feeling long. Pair this with disciplined test review, because knowing which tricks you forgot under pressure is what actually moves your score.
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Percentage-fraction equivalents like 1/7 = 14.28% and 1/8 = 12.5%, which let you replace long multiplication with quick division.
Net% = a + b + ab/100. It handles two successive changes, discount-on-discount and growth problems in a single step.
Converting the work to LCM-based integer units avoids adding fractions under pressure, making the calculation faster and far less error-prone.
Spend 10 focused minutes a day on tables, squares and cubes, then apply them in timed topic tests until recall becomes automatic.
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