AIIMS CRE cheat sheet

Letter positions: A=1, B=2, …, Z=26. Opposite pairs sum to 27 (A↔Z, B↔Y, …, M↔N).

Number series: check differences (1st, 2nd order), ratios, alternating patterns, squares/cubes, and prime sequences before assuming a complex rule.

Coding-decoding: for letter-shift codes, compute the numeric shift per letter; if shifts vary, test position-based rules (e.g., shift = position of letter in word).

Blood relations: draw a family tree with gender markers; use '+' for male, '−' for female, and horizontal lines for siblings, vertical for parent-child.

Direction sense: net displacement = vector sum; use Pythagoras for right-angle turns. Facing north, right = east, left = west; facing south, right = west, left = east.

Syllogism: a conclusion follows only if it is true in every possible Venn diagram consistent with the premises; 'some A are B' does not imply 'some B are A' unless stated.

Seating arrangement: for linear rows, fix one anchor and place others relative to it; for circular, note that 'left' and 'right' reverse when facing the centre versus facing outward.

Analogy: identify the relationship type (cause-effect, part-whole, synonym, worker-tool, degree) before selecting the matching pair; the relationship must hold in the same direction.

Indian Constitution: adopted 26 November 1949, came into force 26 January 1950; Dr B.R. Ambedkar chaired the Drafting Committee.

Fundamental Rights are in Part III (Articles 12–35); Directive Principles in Part IV (Articles 36–51); Fundamental Duties in Part IVA (Article 51A, added by the 42nd Amendment, 1976).

Indian Parliament: Lok Sabha maximum strength 552 (530 states, 20 UTs, 2 Anglo-Indians nominated; the Anglo-Indian nomination lapsed in 2020); Rajya Sabha maximum 250 (238 elected, 12 nominated).

RBI was established on 1 April 1935 under the RBI Act, 1934; it was nationalised in 1949. Monetary policy is set by the six-member Monetary Policy Committee (MPC).

Space: ISRO's Chandrayaan-3 landed near the lunar south pole on 23 August 2023; Aditya-L1, India's first solar observatory, was launched on 2 September 2023.

Key dates: National Science Day 28 February; National Technology Day 11 May; World Environment Day 5 June; International Yoga Day 21 June.

Sports: the Olympic Games are held every four years; the 2024 Summer Olympics were in Paris; the 2028 Summer Olympics will be in Los Angeles.

Economics: GDP = C + I + G + (X − M); fiscal deficit = total expenditure − total receipts excluding borrowings; repo rate is the rate at which RBI lends to banks.

Percentage change = (new − old)/old × 100; successive percentage changes of a% and b% give a net change of a + b + ab/100.

Profit and loss: profit% = profit/CP × 100; selling price = CP × (100 + profit%)/100; discount% is always calculated on marked price.

Simple interest SI = P × R × T / 100; compound interest CI = P[(1 + R/100)^T − 1]; for 2 years, CI − SI = P(R/100)^2.

Time-speed-distance: distance = speed × time; to convert km/h to m/s multiply by 5/18; for a train crossing a platform, total distance = train length + platform length.

Averages: average = sum/count; if every value is increased by k, the average increases by k; if every value is multiplied by k, the average is multiplied by k.

Ratio and proportion: if a:b = c:d then ad = bc; to divide amount N in ratio a:b:c, shares are N×a/(a+b+c), N×b/(a+b+c), N×c/(a+b+c).

Permutations and combinations: nPr = n!/(n−r)!; nCr = n!/[r!(n−r)!]; nC0 = nCn = 1; nCr = nC(n−r).

Mensuration: area of circle = πr²; circumference = 2πr; volume of cylinder = πr²h; volume of sphere = (4/3)πr³; total surface area of cube = 6a².

Subject-verb agreement: a singular subject takes a singular verb; compound subjects joined by 'and' take a plural verb unless they form a single idea (e.g., 'bread and butter is').

Articles: use 'a' before consonant sounds, 'an' before vowel sounds (an hour, a university); 'the' for specific or previously mentioned nouns and superlatives.

Prepositions of time: 'in' for months, years, seasons; 'on' for days and dates; 'at' for clock times and specific points (at noon, at night).

Tenses: present perfect (has/have + past participle) for past actions with present relevance; past perfect (had + past participle) for the earlier of two past actions.

Active to passive: move the object to subject position, use the correct form of 'be' + past participle, and add 'by' + agent when relevant.

Common error traps: 'one of the' takes a plural noun but a singular verb; 'each', 'every', 'either', 'neither' are singular; 'none' can be singular or plural depending on context.

Synonyms and antonyms: use context clues (contrast words like 'but', 'although'; cause-effect words like 'therefore') to infer meaning rather than memorised lists.

Reading comprehension: identify the main idea, tone, and author's purpose; answer must be supported by the passage, not by outside knowledge.