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Defence

Mathematics for CDS

Elementary Mathematics is 100 questions in two hours at about Class 10 level. IMA, INA and AFA candidates take it; OTA-only candidates don’t. It covers arithmetic, algebra, trigonometry, geometry, mensuration and statistics, and speed and short methods decide the score.

10 guides·Conducted by Union Public Service CommissionOfficial website

Study in this order

  1. 1An elementary mathematics plan for CDSCDS maths is Class 10 level (arithmetic, algebra, trigonometry, geometry, mensuration and statistics) tested for speed in 100 questions and two hours. What the syllabus covers, a 12-week order of study, daily practice, sample questions with fast methods, and exam-day tactics. 7 min read
  2. 2The number system for CDSDivisibility rules, unit digits, factors, remainders, primes and sums of series: the number system questions CDS asks in most papers. Each rule explained with why it works, six worked questions and a practice set. 8 min read
  3. 3HCF and LCM for CDSHCF for "largest", LCM for "smallest", and the product rule that links them. Prime factorisation, the division method, remainder problems, bells and tiles, with six worked CDS-level questions and a practice set. 7 min read
  4. 4Fractions, decimals and square roots for CDSComparing fractions, recurring decimals, square and cube roots, surds and rationalising. Quick methods with the reasons behind them, six worked CDS-level questions and a practice set. 6 min read
  5. 5Simplification for CDSBODMAS, "of", decimals, continued fractions and the algebraic identities that turn long expressions into quick answers. Methods with reasons, six worked CDS-level questions and a practice set. 6 min read
  6. 6Percentage for CDSSuccessive changes, "more than" and "less than", population growth, price and consumption, elections and pass marks: the percentage problems CDS keeps returning to. Methods with reasons, six worked questions and a practice set. 6 min read
  7. 7Profit, loss and discount for CDSCost price, marked price, discounts, dishonest dealers and "the selling price of 12 equals the cost price of 15". CDS profit and loss built on multipliers, with six worked questions and a practice set. 7 min read
  8. 8Simple and compound interest for CDSSimple interest as a straight line, compound interest as a multiplier, the CI minus SI difference, half-yearly compounding and doubling time. Six worked CDS-level questions and a practice set. 6 min read
  9. 9Ratio, proportion and variation for CDSDividing in a ratio, combining ratios, proportionals, componendo and dividendo, incomes and savings, and direct, inverse and joint variation. Six worked CDS-level questions and a practice set. 6 min read
  10. 10Averages and mixtures for CDSThink in totals, not averages. Correcting a wrongly copied value, a new member replacing an old one, required scores, alligation with profit, and repeated replacement. Six worked CDS-level questions and practice. 6 min read

New Mathematics guides are added regularly. Back to all CDS guides