General Science & Environment
pH Memory Trick — Acids are pH 0-7 (think "A" comes before "7"), bases 7-14. Pure water = 7. Lemon ~2, blood ~7.4, bleach ~13. Remember: lower number = stronger acid.
Vitamin Deficiency Chain — A-Night, B1-Beri, C-Scurvy, D-Bone, K-Klot. A for night blindness, B1 for beriberi, C for scurvy, D for bone issues (rickets), K for blood clotting.
Planet Order — My Very Educated Mother Just Served Us Nachos (Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune). For size order: Jupiter, Saturn, Uranus, Neptune, Earth, Venus, Mars, Mercury.
Reactivity Series Top-5 — Please Stop Calling Me A (Potassium, Sodium, Calcium, Magnesium, Aluminium) — most reactive metals, displace hydrogen from water/acids easily.
Biology
Mitosis Phases — PMAT: Prophase, Metaphase, Anaphase, Telophase. Chromosomes appear, align at center, are pulled apart, then two nuclei form. Meiosis does PMAT twice.
Blood Group Compatibility — O is donor, AB is acceptor. O-negative = universal donor (gives to all), AB-positive = universal recipient (takes from all). Remember: O has nothing to give antibodies to.
Cranial Nerve Count — Humans have exactly 12 pairs of cranial nerves. Mnemonic for names: On Old Olympus Towering Tops (Olfactory, Optic, Oculomotor, Trochlear, Trigeminal...).
Chemistry
BODMAS Trap in Chemical Equations — Balance atoms not coefficients first. In redox: OIL RIG (Oxidation Is Loss, Reduction Is Gain of electrons). LEO goes GER also works (Lose Electrons Oxidation, Gain Electrons Reduction).
Periodic Table Groups — Group 1: Alkali metals (Li, Na, K, Rb, Cs, Fr). Group 17: Halogens (F, Cl, Br, I, At). Group 18: Noble gases (He, Ne, Ar, Kr, Xe, Rn). Remember positions for exam MCQs.
Electrolysis Memory — PANCHO: Positive Anode Negative Cathode (Oxidation at anode, reduction at cathode). Anions move to anode, cations to cathode—opposites attract.
Arithmetic
Divisibility by 11 — Subtract alternating digits. If result is 0 or 11 multiple, number divides by 11. Example: 121 → 1-2+1=0, divisible. For 1331 → 1-3+3-1=0, divisible.
Percentage-Fraction快速 Conversions — 12.5%=1/8, 16.67%=1/6, 20%=1/5, 25%=1/4, 33.33%=1/3, 50%=1/2, 66.67%=2/3, 75%=3/4. Memorize these nine for instant calculation.
Compound Interest Shortcut — For 2 years: CI-SI difference = P(R/100)². If SI=1000 and R=10%, extra CI = 1000×(10/100)² = ₹10. Works only for 2-year problems.
Square of Numbers Ending in 5 — For n5: n×(n+1) followed by 25. Example: 75² → 7×8=56, append 25 = 5625. Works for 25, 35, 45, 65, 85, 95, 105 instantly.
Geometry & Mensuration
Triangle Area Without Height — Heron's formula: s = (a+b+c)/2, then Area = √[s(s-a)(s-b)(s-c)]. When sides given but no height, use this. Remember the "s" semi-perimeter first.
Angle Sum Shortcut — Triangle=180°, Quadrilateral=360°, Pentagon=540°. Formula: (n-2)×180° for n-sided polygon. Hexagon=720°, Heptagon=900°. Each time add 180°.
Cylinder-Cone-Sphere Volumes — For same radius r and height h: Cylinder=πr²h, Cone=(1/3)πr²h, Sphere=(4/3)πr³. Ratio is 3:1:2 when h=2r for comparison.
Logical Reasoning & Analytical Ability
Direction Sense Shortcut — Draw NEWS clockwise (North-East-West-South is wrong!). Correct: N-E-S-W clockwise or remember "WNES" anti-clockwise. Right turn from North = East.
Clock Angle Formula — Angle = |11M/2 - 30H| where H=hour, M=minute. At 3:15: |11×15/2 - 30×3| = |82.5-90| = 7.5°. For exact angles in clock problems.
Coding-Decoding Pattern — If CAT=3120, most likely A=1, B=2... Z=26. Check if letters converted to position numbers then added/multiplied. Try reverse alphabet (A=26, Z=1) if normal fails.
Time, Speed & Work
Relative Speed Rule — Same direction: subtract speeds. Opposite direction: add speeds. Train crossing: add lengths before dividing by relative speed. Two trains meeting: distance/(S1+S2).
Work Efficiency Inverse — If A does work in 10 days, B in 15 days: ratio of efficiency = 15:10 = 3:2 (inverse of days). Together: 1/10 + 1/15 = 5/30 = 6 days.
Speed Conversion — km/h to m/s: multiply by 5/18. m/s to km/h: multiply by 18/5. Remember: 36 km/h = 10 m/s (exactly). 72 km/h = 20 m/s.
Madhya Pradesh — Special Knowledge
MP Border States Mnemonic — CHRUNG: Chhattisgarh, (U)ttar Pradesh, Rajasthan, Gujarat, Maharashtra. MP touches 5 states—largest shared border with Maharashtra (longest state border in India).
Major Rivers of MP — NSC-TB: Narmada, Son, Chambal, Tapti, Betwa. Narmada flows westward (exception in India), Chambal famous for ravines, Son flows to Ganga. Narmada is MP's lifeline.
MP Tribes Major 3 — BGB: Bhil, Gond, Baiga. Bhils in western MP (Jhabua, Alirajpur), Gonds in eastern (Mandla, Dindori), Baigas in Balaghat. Together ~20% of MP population.
MP Mineral Wealth — Diamond-Copper Triangle: Panna (only diamond mine in India), Malajkhand (copper), Singrauli (coal), Jabalpur (limestone/marble). "PMSJ" for locations in exams.