Strategy
Score 100+ in NDA Maths with 50 hours of focused prep
120 questions × 2.5 marks − 0.83 per wrong. Here's the math, then the chapters.
- marks out of 300
- 100+
- attempts of 120
- 50
- accuracy needed
- 85%
- total prep time
- ~47 h
The arithmetic of 100+
NDA Mathematics has 120 questions worth 2.5 marks each, with −0.83 per wrong answer. To net 100 marks you need (correct × 2.5) − (wrong × 0.83) ≥ 100. Plug in realistic accuracy:
| Accuracy | Attempts | Correct | Wrong | Net marks | Result |
|---|---|---|---|---|---|
| 80% | 50 | 40 | 10 | 91.7 | Miss |
| 85% | 50 | 42.5 | 7.5 | ~106 | Target ✓ |
| 90% | 47 | 42.3 | 4.7 | ~107 | Comfortable ✓ |
Target: attempt 50 questions at ≥85% accuracy. Skip the other 70. This means picking the right 50 chapters’ worth of preparation — not “doing all 31 chapters”. The data below tells you exactly which 50.
Tier A — the foundation (6 chapters, ~38 q/paper)
Must-master, no skipping. These chapters share three properties: high q-count, high easy/moderate ratio, and reliable appearance every paper. Together they account for 680 questions (31% of the bank) and ~38 questions per paper. Probability joined Tier A in 2026-05 after the 2017–2026 expansion confirmed its 9 q/paper rate.
Statistics
160 questions · 49% easy · 13% hard
Formula substitution. The lowest-difficulty chapter in the bank (49% EASY) — your highest marks-per-hour pickup.
Drill
Skip
- Regression and Correlation
Matrices & Determinants
170 questions · 24% easy · 31% hard
Highest-reliability chapter — always 8–11 q per paper. Master determinant evaluation + adjoint and you've banked a third of your target.
Drill
Skip
- Special Determinants — Trig, Complex, Roots of Unity, Polynomial
- Linear Systems — Consistency, Cramer's Rule, Solution Space
Probability
162 questions · 30% easy · 17% hard
Promoted to Tier A — 162 q, mostly classical (30% EASY, only 17% HARD). Sample-space construction is the actual work; Bayes/event-algebra are the harder slice — skip them on first pass.
Skip
- Conditional Probability, Total Probability, and Bayes' Theorem
- Event Algebra — Inclusion-Exclusion, Mutually Exclusive, Exhaustive
Sequence & Series
89 questions · 31% easy · 21% hard
AP / GP / HP plus the AM-GM-HM inequality chain. Six formulas cover ~90% of what's asked; AM-GM is the cross-chapter lever.
Skip
- Special Series and Special Sums
Sets & Relations
69 questions · 32% easy · 13% hard
Inclusion-exclusion + basic relation properties. The easiest 2-3 marks in NDA Maths if you give it 2 hours.
Binomial Distribution
30 questions · 27% easy · 10% hard
Tiny chapter, one formula. P(X=k) = C(n,k)·p^k·q^(n-k); mean=np, var=npq. 60 minutes, 2 marks guaranteed.
Tier B — selective drill (4 chapters, ~23 q/paper)
Cover only the easier subtopics here. The hard subtopics in these chapters are time-sinks — leave them and pick up Tier A marks instead. Trig Identities is the cherry-pick newcomer: 138 q but only the compound-angle and specific-values subtopics earn study time.
Functions
109 questions · 44% easy · 10% hard
High-easy ratio (44% EASY, only 10% HARD). Stick to domain/range and composition; functional equations are a time-sink.
Skip
- Functional Equations
- Greatest Integer Function
Complex Numbers
72 questions · 29% easy · 22% hard
Modulus/argument is half the chapter. Drill cube-roots-of-unity (ω³ = 1, 1+ω+ω² = 0) — it shows up in M&D too.
Drill
- Modulus, Argument, and ConjugateDrill
Skip
- Powers and Roots
Vectors
97 questions · 28% easy · 20% hard
Four formulas: dot, cross, scalar triple, magnitude. Vector-geometry questions are time-traps; skip them.
Skip
- Vector Geometry — Triangles, Parallelograms, Quadrilaterals
Trigonometric Identities
138 questions · 24% easy · 34% hard
Demoted from skip-list to cherry-pick. Big chapter (138 q) but 34% HARD overall — drill only compound-angle and specific-values (the two foundational subtopics, ~60 q of EASY+MOD). Skip multi/half-angle (50% HARD principle), product-to-sum, and max/min (AM-GM territory).
Skip
- Multiple and Half-Angle Formulas
- Maximum and Minimum of Trigonometric Expressions
- Product-to-Sum and Sum-to-Product Identities
Skip list — 21 chapters
These chapters yield poor marks-per-hour. Browse them once for free wins on test day, but don’t deep-study. The 10 Tier A+B chapters above give you the 50 attempts you need.
- Properties of Triangle45% hard. Punishing yield.49q45% hard. Punishing yield.
- Height & Distance71% hard — the hardest chapter in the bank.24q71% hard — the hardest chapter in the bank.
- Quadratic Equations40% hard. Better time spent on M&D.63q40% hard. Better time spent on M&D.
- Indefinite IntegrationOnly 6 easy questions across the bank.40qOnly 6 easy questions across the bank.
- Application of DerivativesMonotonicity/Extrema dominates; AM-GM lever is faster than derivatives.73qMonotonicity/Extrema dominates; AM-GM lever is faster than derivatives.
- Inverse TrigonometryHard formulas, only ~1.9 q/paper.34qHard formulas, only ~1.9 q/paper.
- Differential Equations29% hard; separable + IVP only if time permits.63q29% hard; separable + IVP only if time permits.
- DifferentiationTime-consuming for moderate yield; chain-rule the only must-know.85qTime-consuming for moderate yield; chain-rule the only must-know.
- Limits & ContinuityHeavy passage usage; piecewise/modulus is hard despite 14% HARD label.81qHeavy passage usage; piecewise/modulus is hard despite 14% HARD label.
- Definite IntegrationProperties (King's, symmetry) are drillable but passage-heavy.66qProperties (King's, symmetry) are drillable but passage-heavy.
- Applications of IntegrationNiche; ~1.4 q/paper, often missed.25qNiche; ~1.4 q/paper, often missed.
- Linear Inequalities0.3 q/paper avg — near-irrelevant.5q0.3 q/paper avg — near-irrelevant.
- Binary Numbers0.7 q/paper avg.13q0.7 q/paper avg.
- Logarithms1.5 q/paper. 30-min log-laws refresher only.27q1.5 q/paper. 30-min log-laws refresher only.
- Trigonometric Equations33% hard, only 1.8 q/paper.33q33% hard, only 1.8 q/paper.
- Permutation & CombinationTricky counting. Time-intensive vs yield.78qTricky counting. Time-intensive vs yield.
- Binomial TheoremFormula-heavy but tricky; coefficient identities the only must-know.54qFormula-heavy but tricky; coefficient identities the only must-know.
- ConicsGeometry-heavy.38qGeometry-heavy.
- Circles41% hard. Only 1.5 q/paper.27q41% hard. Only 1.5 q/paper.
- LinesCoordinate geometry — moderate difficulty but spread thin across subtopics.97qCoordinate geometry — moderate difficulty but spread thin across subtopics.
- 3D GeometryTouch only Direction Cosines if time permits.89qTouch only Direction Cosines if time permits.
Test-day attempt order
Don’t go in paper order. Scan the entire paper, mark Tier A questions, then attack:
- 30min
Sweep your strong chapters
Scan all 120 questions. Solve every Statistics, M&D, Probability, Binomial Distribution, Sets, and Sequence & Series question in that order. Target: 28–32 correct in 30 minutes.
- 60min
Tier B
Tackle marked Functions, Complex Numbers, Vectors, and Trig-Identities (compound-angle + specific-values) questions. Target: 12–16 more correct.
- 30min
Cherry-pick
Scan unsolved questions in skip-list chapters for obvious wins (single-step formula, no setup). If a question takes more than 90 seconds to set up — skip it. Each wrong answer costs you a third of a correct one.
Never attempt a question whose method you don’t recognise in 30 seconds. Three unlucky guesses wipe out a correct answer’s worth of marks.
Time investment plan
| Tier | Hours | Outcome |
|---|---|---|
| Tier A (6 chapters) | 20 | ~38 questions per paper |
| Tier B (4 chapters) | 11 | ~23 questions per paper |
| Skip-list cherry picks | 4 | ~5 bonus questions |
| Past papers, timed (5 papers) | 12.5 | Calibration + speed |
| Total | 47.5 | Target: 100–115 marks |
That’s roughly 6 weeks at 7 hours/week. Much less than the “do everything” approach — which typically takes 150+ hours and still scores 80–100 because attention’s spread too thin.
Start with Tier A — Statistics
Highest marks-per-hour. 4 hours, 7–8 marks expected per paper.