Analytical Ability
CLUE for Blood Relations — Child-Level-Up-Elder: Always draw family tree moving upward (parents, grandparents) or downward (children). Mark gender (△ male, ○ female) and generation levels to avoid confusion in complex chains.
Clock Method for Circular Arrangement — In clockwise arrangements, person A's right neighbor sits where clock hand moves next; left neighbor sits opposite. Number positions 1-8 like clock hours to track "opposite" (differ by 4) and "adjacent" seats instantly.
A1Z26 for Coding — A=1, B=2...Z=26. For letter-shift codes, identify the constant (+3, -2, ×2 pattern). For number codes, check place-value sum (CAT: 3+1+20=24). Reverse alphabet: A↔Z, B↔Y (A=26, Z=1).
BODMAS Trap in Data Sufficiency — When statements give equations, don't solve fully—just check if unique solution exists. Example: Two variables need two independent equations; one equation = insufficient alone, both together = sufficient.
Date Anchor: January 1st — Memorize Jan 1 day for current year (2024=Monday). Odd days: Jan-Feb=31+29=60 (1 odd day in leap year). Every month-end adds odd days: use knuckle trick (knuckle=31 days) to track.
NSEW Box for Direction Sense — Draw quick compass. Right turn = clockwise 90°. "Faces North, right turn, walks" = now facing East. Double the distance statements mentally: "10m N, 10m S" = cancel out = origin point.
Data Interpretation: Percentage Shortcut — For "% increase from A to B": (B−A)/A × 100. Quick: If 80→100, increase = 25%. If 100→80, decrease = 20% (not 25%—different bases). Pre-calculate 10%, 20%, 50% benchmarks from given totals.
Pie Chart: Angle-to-Percentage — 360° = 100%. Each 3.6° = 1%. Angle 72° = 20%, 90° = 25%, 120° = 33.33%, 180° = 50%. Visual estimation: quarter-circle = 25%, half = 50%, one-third ≈ 120°.
Series Pattern: Difference of Differences — For 2, 5, 10, 17, 26: find first difference (3,5,7,9), then second difference (2,2,2). Constant second difference = quadratic series. For ratio series, divide consecutive terms to spot ×2, ×3 patterns.
Venn Diagram: n(A∪B) — Formula: n(A∪B) = n(A) + n(B) − n(A∩B). For three sets: add all, subtract pairs, add back triple intersection. "Only A" = n(A) − overlaps. Always verify total = sum of all regions.
Mathematical Ability
Divisibility by 11 — Alternating digit sum: (sum odd positions) − (sum even positions). Example: 2728 → (2+2)−(7+8) = −11, divisible. If result is 0 or multiple of 11, number is divisible by 11.
Indices MADSPM Rule — Multiply=Add powers, Divide=Subtract, Power-to-power=Multiply. a^m × a^n = a^(m+n); (a^m)^n = a^(mn). Negative exponent: a^(−n) = 1/a^n. Zero power: a^0 = 1 (a≠0).
Binomial (a+b)² Traps — (a+b)² = a² + 2ab + b² (NOT a²+b²). (a−b)² = a² − 2ab + b². (a+b)(a−b) = a²−b². Common error: forgetting middle term 2ab in expansions.