Reasoning and Mental Ability
Clockwise Direction Rule — From North, clockwise order is N→E→S→W. Right turn = next in sequence, Left turn = previous. 180° turn = opposite (N↔S, E↔W). Quick mental compass for direction problems.
Coding +/- Pattern — If A=1, Z=26: check if letters shift forward/backward by fixed number. Example: CAT → DBU means +1 shift. Always verify first and last letters first.
Blood Relations Parent Trick — Mother's/Father's side: if "maternal" appears = mother's family; "paternal" = father's family. Mother-in-law = wife's mother (not husband's). Draw small family tree for complex chains.
Odd One Out: Count Properties — In figural classification, count: number of sides, enclosed spaces, symmetry lines, or curves. The figure with different count is the answer. Works 70% of the time.
Series Gap Method — In number series, write differences between consecutive terms. If differences don't show pattern, check differences of differences (second-order). Usually reveals arithmetic or geometric pattern.
Ranking from Ends Formula — Total persons = (Rank from left + Rank from right) - 1. If overlap exists, subtract 1. Quick verification for order and ranking problems.
Arithmetic and Quantitative Aptitude
Divisibility by 11 Trick — Alternating sum: (sum of odd-position digits) - (sum of even-position digits) must be 0 or multiple of 11. Example: 121→(1+1)-2=0, divisible.
Percentage-Fraction Conversion — Memorize: 12.5%=⅛, 16.67%=⅙, 20%=⅕, 25%=¼, 33.33%=⅓, 50%=½, 66.67%=⅔. Saves calculation time in profit-loss and discount problems.
SI vs CI First Year — Simple Interest and Compound Interest are EQUAL in first year. Difference appears from year 2. CI-SI for 2 years = P(R/100)², quick formula.
Time-Speed-Distance Triangle — Draw triangle: Distance on top, Speed and Time at bottom. Cover what you need; remaining shows formula. D=S×T, S=D/T, T=D/S.
Ratio Multiplication Shortcut — To compare A:B and B:C, make B equal. Example: 2:3 and 4:5 → multiply first by 4, second by 3 → 8:12:15. Useful for partnership problems.
Alligation Cross Method — For mixture problems: draw X, write mean in center, cheaper on left, costlier on right. Cross-subtract: ratio = (dearer-mean):(mean-cheaper). Direct answer for average questions.
Work Formula: M₁D₁H₁/W₁ = M₂D₂H₂/W₂ — Men, Days, Hours, Work relation. If men increase, days decrease (inverse). If work increases, days increase (direct). Solves 90% time-work problems.
Profit % on CP vs SP — Profit% on Cost = (Profit/CP)×100. On Selling = (Profit/SP)×100. If SP=120, CP=100, profit=20: on CP=20%, on SP=16.67%. Exam tricks often confuse these.