Reasoning and Mental Ability
Coding-Decoding: Position Value Trick — For letter-to-number: A=1, Z=26. Reverse: A=26, Z=1. Quick check: M is always 13 (middle), N is 14 forward or 13 reverse. For EJOTY pattern, remember Every Jumbo Otter Teaches You.
Direction: NEWS Clockwise — Never Eat Wet Socks. Clockwise from top: N-E-S-W. Right turn = next clockwise direction. Left turn = previous. 180° turn = opposite (N↔S, E↔W). Two rights = one 180°.
Blood Relations: Generation Shortcut — Plus generation (+): father, mother, uncle, aunt. Minus generation (−): son, daughter, nephew, niece. Same generation (0): brother, sister, cousin, spouse. Saves confusion in chain problems.
Dice: Opposite Faces Sum to 7 — On standard dice, opposite faces always total 7: 1↔6, 2↔5, 3↔4. If two adjacent faces shown, the third visible face is NOT opposite to hidden ones. Eliminates 2-3 options instantly.
Seating Arrangement: Circular Clock Method — In circular tables, fix one person at 12 o'clock position. Count clockwise for "right," anti-clockwise for "left." Opposite person is 6 positions away in 12-seat, 3 away in 6-seat.
Syllogism: "Some" Statements Never Conclude "All" — If premises have only "Some," conclusion can't be "All" or "No." If one premise is negative, conclusion must be negative. Two negatives = no valid conclusion. Two particulars ("Some") = no conclusion.
Quantitative Aptitude
Number System: Divisibility by 11 — Alternating digit sum: (sum of odd-position digits) − (sum of even-position digits). If result is 0 or multiple of 11, number is divisible by 11. E.g., 1331: (1+3)−(3+1)=0 ✓
Percentage: 10%-1% Breakdown — For complex percentages, find 10% (shift decimal left), then 1% (divide by 10). Build any %: 17% = 10%+5%+2%. Saves calculator dependence; faster than formula in MCQs.
Simple Interest: Doubling Money Formula — Money doubles when (Rate × Time)/100 = 1. So Time = 100/Rate or Rate = 100/Time. At 5% SI, doubles in 20 years. At 10%, doubles in 10 years. Instant answer for "when doubles" questions.
Time-Speed-Distance: 5/18 Conversion — km/h to m/s: multiply by 5/18. m/s to km/h: multiply by 18/5. Remember 72 km/h = 72×5/18 = 20 m/s (benchmark). Train problems always need this conversion.
Profit-Loss: Successive Discount Formula — Two discounts d₁% and d₂%: Net = d₁ + d₂ − (d₁×d₂)/100. For 20% + 10%: 20+10−(200/100) = 28% net discount, NOT 30%. Crucial for discount chains.
Time-Work: Efficiency Ratio Inverse — If A takes 3 days, B takes 6 days, efficiency ratio A:B = 6:3 = 2:1 (inverse of time). Total work = LCM(3,6)=6 units. A does 2 units/day, B does 1 unit/day.
Geometry: Pythagorean Triplets — Memorize: 3-4-5, 5-12-13, 8-15-17, 7-24-25. Multiples also work: 6-8-10, 9-12-15. Instantly spot right triangles without calculation; saves 30+ seconds per question.