BharatNotes CSAT maths is dominated by Number System (~20% of the entire paper across the last 10 years — 87 questions). After that, Percentages (26 PYQs), Divisibility & Remainders (22), Time & Work, Profit & Loss, Ratio & Proportion, Averages, and Mensuration round out the high-yield list. CSAT 2025 alone drew 25 questions from Number System. If you have limited time, the order is: Number System > Percentages > Time/Work/Distance > Ratios > Averages > Mensuration > Probability.
The 10-year topic table
Aggregated from Testbook's trend analysis (2014–2025), PrepAiro topic-wise weightage, and IAS Setu PYQ banks. Question counts are approximate because some questions span two topics.
| Topic | ~10-year PYQ count | Share of maths section | Difficulty |
|---|---|---|---|
| Number System (HCF/LCM, divisibility, digits, factors) | 87 | ~28% | High variance |
| Percentages | 26 | ~8% | Medium |
| Divisibility & Remainders | 22 | ~7% | Medium-hard |
| Time, Work & Distance | ~20 | ~6% | Medium |
| Profit, Loss & Discount | ~15 | ~5% | Easy-medium |
| Ratio & Proportion | ~15 | ~5% | Easy |
| Averages, Mixtures & Alligation | ~12 | ~4% | Medium |
| Mensuration (area, volume) | ~12 | ~4% | Easy-medium |
| Permutation, Combination, Probability | ~10 | ~3% | Hard |
| Algebra (linear, quadratic basics) | ~8 | ~3% | Medium |
| Geometry (Class IX–X) | ~6 | ~2% | Easy |
| Number series & progressions | ~6 | ~2% | Easy |
Why Number System dominates
Number System is the base layer for almost every other maths topic. HCF/LCM problems, divisibility rules, prime factorisation, digit-sum logic, last-digit cyclicity — all show up disguised inside percentage, ratio and time-work problems. CSAT 2025 explicitly had 25 questions from Number System alone (across direct and applied forms). Mastering this one topic raises your maths attempt rate more than any other intervention.
The four-topic 70-mark plan
If you can prepare only four maths topics, this combination historically gives a CSAT attempt of 25+ correct (62.5 marks raw from maths alone):
- Number System — HCF/LCM, factors, divisibility, remainders, digit problems, prime sequences
- Percentages — successive change, increase/decrease, conversion to fractions
- Time, Work, Speed, Distance — basic work units, relative speed, trains-and-platforms, upstream/downstream
- Ratio & Proportion + Averages — paired together because half the average questions are ratio problems in disguise
Layer Mensuration and Profit-Loss for an extra 5–6 questions; touch Probability only if comfortable.
Worked attempt math
Assume you've prepped only the four topics above. Realistic CSAT 2025-style mock attempt:
- Number System: 8 correct, 2 wrong (out of 10 attempted, ~25 in paper)
- Percentages: 4 correct, 1 wrong
- Time/Work/Distance: 4 correct, 1 wrong
- Ratio/Average: 4 correct, 1 wrong
That is 20 correct + 5 wrong on maths alone. Net from maths = 20 × 2.5 − 5 × 0.833 = 45.83 marks. Add 22 RC correct (55 marks) and 5 reasoning correct (12.5 marks), and you have ~113 marks — well above 66.
NCERT chapters that actually matter
For each high-yield topic, the underlying NCERT base:
- Number System — Class 6 Chapter 3 (Whole Numbers), Class 7 Chapter 1 (Integers), Class 8 Chapter 6 (Squares & Cubes), Class 9 Chapter 1 (Number Systems), Class 10 Chapter 1 (Real Numbers — Fundamental Theorem of Arithmetic).
- Algebra — Class 8 Chapter 9, Class 9 Chapter 2, Class 10 Chapters 3 & 4 (linear and quadratic).
- Mensuration — Class 8 Chapter 11, Class 9 Chapter 12, Class 10 Chapter 11.
- Probability — Class 9 Chapter 14, Class 10 Chapter 13.
Three weeks on these is a stronger base than a month with R.S. Aggarwal alone.
Mentor's takeaway
Do not prepare maths chapter-by-chapter from a 700-page CSAT manual. Pareto it. Four topics give you 70+ marks of attempt-capacity; that alone qualifies you. Add depth only after those four are mock-proof.
