Quantitative Aptitude Tricks for Banking & SSC — Speed Math Techniques

Learn speed math techniques and shortcuts for Data Interpretation, Percentage, Profit-Loss, Time-Work, and Number Series for Banking and SSC exams.

Speed Math — The Foundation

Learn tables up to 30. This alone saves 2-3 minutes per exam.
Learn squares up to 30 and cubes up to 15. Frequently tested in simplification.
Percentage to fraction: 12.5% = 1/8, 16.67% = 1/6, 33.33% = 1/3, 37.5% = 3/8, 62.5% = 5/8.
Multiply by 11 trick: 36 × 11 = 3(3+6)6 = 396. For 2-digit numbers, sum middle digits.
Square of numbers ending in 5: 75² = 7×8 | 25 = 5625. (Multiply first digit by next, append 25).

DI carries 15-20 marks in banking exams. Master this to guarantee 15+ marks.
Step 1: Read the data carefully for 30-60 seconds before touching questions.
Step 2: Approximate! In DI, exact calculation is rarely needed. Round to nearest 5 or 10.
Step 3: Use fraction shortcuts. 1/4 of 840 ≈ 210. 1/3 of 960 ≈ 320.
For percentage change: (Difference/Base) × 100. Always use the old value as base.
For ratio-based DI: Convert all values to the same denominator first.
Time target: 5 DI questions in 8-10 minutes maximum.

Master formula: SP = CP × (100 ± P/L%) / 100.
Successive discount: Two discounts of a% and b% = (a + b - ab/100)%.
Markup × Discount = Profit: If markup 25% and discount 20%, profit = 25-20-(25×20/100) = 0%.
Dishonest shopkeeper: Uses 900g weight instead of 1000g. Profit = (100/900) × 100 = 11.11%.
Buy 3 Get 1 Free = 25% discount (you pay for 3, get value of 4).

LCM method is 10x faster than fraction method. Take LCM of days as total work.
Example: A does in 12 days, B in 15 days. LCM(12,15) = 60 units total work.
A per day = 60/12 = 5 units. B per day = 60/15 = 4 units. Together = 9 units/day.
Days together = 60/9 = 6.67 days. Done in seconds instead of minutes with fractions.
Pipes & Cisterns: Same logic. Filling pipe = positive work. Draining pipe = negative work.

Common patterns: +constant, ×constant, +increasing, ×increasing, alternating, nested.
First check: Differences between consecutive terms. If constant = Arithmetic series.
Second check: Ratios between consecutive terms. If constant = Geometric series.
Third check: Differences of differences. If constant = Quadratic series.
For complex series: Check if it is a combination (e.g., ×2+1, ×2+3, ×2+5...).
Prime number series, square series, cube series — memorize first 20 of each.