History
Vedic Period Texts — Remember "VBAS" for chronological order: Vedas → Brahmanas → Aranyakas → Sutras. This follows the evolution from hymns to rituals to forest texts to aphorisms.
Six Vedangas — "SSK-CVJ" mnemonic: Shiksha (phonetics), Shrauta/Sulba (rituals/geometry), Kalpa (procedures), Chhanda (metrics), Vyakarana (grammar), Jyotisha (astronomy). Essential auxiliary disciplines of Vedic study.
Buddhist Council Locations — "RKPP" sequence: Rajagriha (1st), Kashmir (4th), Pataliputra (2nd & 3rd). First council immediately after Buddha's death; helps anchor timeline of early Buddhism.
Mughal Succession — "BAH-JASH-BAB" for emperors: Babur, Akbar, Humayun (wait—correct is) Babur-Humayun-Akbar-Jahangir-Shah Jahan-Aurangzeb-Bahadur Shah. Remember "BuHAJA-Shah-Baha" for first seven.
1857 Revolt Centers — "DKLM-BJ" for major centers: Delhi, Kanpur, Lucknow, Meerut, Bareilly, Jhansi. Meerut sparked it (May 10); helps recall geographical spread of uprising.
Geography
Planetary Wind Belts — Remember "0-30-60-90" latitudes: Doldrums (0°), Trade Winds (0-30°), Westerlies (30-60°), Polar Easterlies (60-90°). Pressure belts alternate high-low from equator to poles.
Right-Bank Tributaries of Ganga — "YST-GK" mnemonic: Yamuna, Son, Tons, Ghaghara, Kosi. Left bank has Gomti, Gandak, others. Right-bank tributaries generally come from peninsular/southern side.
Soil Type by Color — Black = Cotton/Regur (volcanic); Red = Crystalline rocks (iron oxide); Laterite = Leached tropical (brick-red); Alluvial = Grey/brown (riverine). Color indicates parent material and climate.
Mangrove Forest States — "WAGA-TOA" for Indian states: West Bengal (Sundarbans—largest), Andhra Pradesh, Gujarat, Andaman, Tamil Nadu, Odisha, Andaman again. West Bengal alone has ~40% of India's mangroves.
Economy
Narrow Money vs Broad Money — M1 = Currency + Demand Deposits (liquid, "narrow"). M3 = M1 + Time Deposits (includes fixed deposits, "broad money"). M1 ⊂ M2 ⊂ M3 ⊂ M4 in increasing liquidity order.
Inflation Types by Speed — Creeping (<3% annually), Walking (3-7%), Running (7-10%), Galloping (double-digit), Hyperinflation (50%+ monthly). Remember as slow walk to sprint. India targets 4% ±2% (walking range).
Deficit Hierarchy — Revenue Deficit (Rev. Expenditure - Rev. Receipts) < Fiscal Deficit (Total Exp. - Total Rev. excluding borrowing) < Primary Deficit (Fiscal Deficit - Interest Payments). Each subset measures worsening fiscal health.
Numerical Ability
Divisibility by 11 — Alternate digit sum rule: (Sum odd-position digits) - (Sum even-position digits) must be 0 or divisible by 11. E.g., 121: (1+1)-(2)=0, divisible. Quick mental check.
Percentage-Fraction Conversions — Memorize: 12.5%=1/8, 16.67%=1/6, 33.33%=1/3, 37.5%=3/8, 62.5%=5/8, 87.5%=7/8. Saves calculation time in competitive exams with answer options.
Square Numbers 1-30 Ending Digits — Squares can only end in 0,1,4,5,6,9. Never 2,3,7,8. Eliminates wrong MCQ options instantly when checking if a number is a perfect square.
Compound Interest Approximation — For small rates, CI ≈ SI + (SI × Rate × Time)/200. E.g., ₹1000@10% for 2 years: SI=200, CI≈200+(200×10×2)/200=₹210. Actual CI=₹210.
General Mental Ability
Direction Sense—Sun Position — Sun rises in East, sets in West. At noon (12 PM IST), sun is in South in Northern Hemisphere. Morning shadow points West; evening shadow points East. Anchor for orientation problems.
Clock Angle Formula — Angle = |30H - 5.5M| degrees, where H=hour, M=minutes. If >180°, subtract from 360°. E.g., 3:15: |90-82.5|=7.5°. Handles "angle between hands" questions instantly.
Blood Relations—Generation Gaps — Uncle/Aunt = 1 generation up, Nephew/Niece = 1 down. Cousin = same generation. Father's brother's son = cousin (same level). Vertical vs horizontal relation anchors family tree puzzles.
Environment and Ecology
Greenhouse Gas Potency — Relative warming: CO₂=1 (baseline), Methane=25×, Nitrous Oxide=300×, CFCs=1000s×. Methane from rice paddies/cattle; N₂O from fertilizers. Helps prioritize mitigation strategies.
Biodiversity Hotspots in India — Four hotspots: Western Ghats + Sri Lanka, Eastern Himalayas, Indo-Burma, Sundaland (Nicobar). Remember "WHIE-S". Must have >1500 endemic plants + lost ≥70% original habitat.
Food Chain Energy Loss — 10% Rule: Only ~10% energy transfers to next trophic level (90% lost as heat/metabolism). Producer→Primary Consumer→Secondary→Tertiary. Explains why fewer top predators exist.