Data Interpretation
Percentage-Fraction Equivalents — Memorize: 1/8=12.5%, 1/6≈16.67%, 1/7≈14.29%, 1/9≈11.11%. Saves calculation time in pie charts and ratio problems during competitive exams.
Average Speed Formula Trap — For equal distances at speeds S1 and S2, average speed = 2S1S2/(S1+S2), NOT (S1+S2)/2. Remember: harmonic mean, not arithmetic mean.
Percentage Change Shortcut — If value increases by x% then decreases by x%, net change = -x²/100. Example: +10% then -10% gives -1% net loss.
Numerical Aptitude
Divisibility by 7, 11, 13 — For 7: Double last digit, subtract from remaining number; repeat till single digit. For 11: Alternating sum of digits. For 13: Add 4× last digit to remaining.
BODMAS Trap Alert — "Of" means multiplication and comes before division. Many fail: 1/2 of 3/4 = 1/2 × 3/4 = 3/8, not 3/8 of anything.
Square Shortcuts (50-60 range) — 52²=2704, 55²=3025, 58²=3364. Pattern: (50+n)² = 2500+100n+n². Memorize 51-59 for rapid calculation.
Compound Interest Approximation — For small rates, 2-year CI ≈ 2R + R²/100. At 5%, two years gives 10.25% (not 10%). R²/100 is the extra interest on interest.
Logical Reasoning
Blood Relations BASE — Brother/Sister (same generation), Aunt/Uncle (one up), Son/Daughter (one down), Extended (two+ levels). Draw generation lines horizontally.
Seating Arrangement Direction — Clockwise = right neighbor; anticlockwise = left neighbor. For circular tables, if A faces center and B is right, B is clockwise from A.
Syllogism Venn Method — "All A are B" = A circle inside B. "No A are B" = separate circles. "Some A are B" = overlapping circles. Draw before concluding.
General Aptitude and Reasoning
Clock Angle Formula — Angle at time H:M = |30H - 5.5M|. Take smaller angle if >180°. At 3:15, angle = |90-82.5| = 7.5°.
Calendar Day Calculation — Odd days: 1 year=1 odd day; leap=2. Century: 1600,2000=0; 1700,1800,1900=5,3,1. Sum odd days, divide by 7 for remainder = day shift.
Direction Sense LURD — Left-Up-Right-Down for 90° rotations. Two lefts = opposite direction. Left then right (or vice versa) maintains original axis.
Indian Economy
Five-Year Plan Eras (Memory) — 1st(1951-Industry base), 2nd(1956-Mahalanobis heavy industry), 7th(1985-Liberalization seeds), 12th(2012-Inclusive growth). Plans discontinued after 12th in 2017.
RBI Monetary Tools "CRIB" — Cash Reserve Ratio, Repo Rate, Incremental CRR (now SDF/MSF), Bank Rate. All four control liquidity and inflation simultaneously.
Welfare Schemes
PM Schemes Acronym "JAY MAK" — PM-JAY (Ayushman), PM-KISAN (farmer income), PM-AWAS (housing), PM-MUDRA (micro-credit), PM-KUSUM (solar agriculture), PM-KAUSHAL (skill training).