The 20 chapters

# Chapter What it covers How often in 2025 Tier 1
1 Number System & HCF/LCM divisibility, remainders, unit digits, factors, HCF and LCM Medium
2 Simplification, Surds & Indices BODMAS, fractions, decimals, square roots, surds, indices Medium
3 Percentage percentage change, successive change, population, expenditure Medium
4 Ratio, Proportion & Partnership ratios, proportion, variation, sharing profit Medium
5 Average weighted average, replacement, ages Medium
6 Mixture & Alligation the alligation rule, repeated replacement Medium
7 Profit, Loss & Discount cost, selling and marked price, successive discount, false weights High
8 Simple & Compound Interest SI, CI, half-yearly interest, instalments Medium
9 Time & Work, Pipes & Cisterns efficiency, wages, leaks Medium
10 Time, Speed & Distance trains, boats and streams, races Medium
11 Algebra identities, surds, a+1aa + \frac{1}{a} type questions, linear equations Low
12 Geometry lines and angles, triangle centres, congruence, similarity, circles, chords, tangents, polygons High
13 Mensuration 2D triangle, quadrilaterals, regular polygons, circle High
14 Mensuration 3D prism, cylinder, cone, sphere, hemisphere, cuboid, pyramid High
15 Trigonometry ratios, identities, complementary angles, degree and radian, maximum and minimum values Medium
16 Height & Distance angles of elevation and depression Low
17 Coordinate Geometry & Linear Graphs graphs of linear equations, intercepts, area Medium
18 Data Interpretation tables, bar, pie and line charts, histogram, frequency polygon Low
19 Statistics mean, median, mode, standard deviation Tier 2 only
20 Probability simple probability Tier 2 only

High means 2 or more questions a shift in 2025. Medium means roughly 1 a shift (0.75 to 2). Low means fewer than 0.75 a shift.

What's inside each chapter

Chapters 1 to 20 all follow the same layout, so you always know where to find things:

  1. Concept notes (a few sections, depending on the size of the topic). The idea explained from the basics, a set of worked Questions with Answers, and a quiz at the end of each section.
  2. Shortcuts & Speed Methods. The quick way to handle each common question type, and when the shortcut does not work.
  3. Solved Questions. 30 or more mixed questions with full answers.
  4. Practice Sets 1, 2 and 3. 25 fresh questions each, every set harder than the one before.
  5. PYQ Practice Sets 1 and 2. 35 questions each that SSC has actually asked on this topic, from CGL 2022 to 2025 (Tier 1 and Tier 2) and Selection Post 2025, mixed across years and question types, all with our own step-by-step answers. The rest of the past questions are used in the mock tests.
  6. Chapter Test. 25 questions to finish in 15 minutes, the same pace as the real Tier 1 section.
  7. Quick Revision. Formulas, rules and common traps as short notes, for the last few days before the exam.

How to work through a chapter

Read the notes and finish each quiz before moving on. Do the Shortcuts section next. Try each Solved Question on your own before reading the answer. Then do the three Practice Sets, followed by the two PYQ Practice Sets with a timer running (about 40 seconds a question), and finish with the Chapter Test.

Keep a notebook of every question you get wrong, with one line on why you got it wrong. Before the exam, that notebook is worth more than any new question.

Which order to study in

The chapters are numbered in the order we suggest, because later chapters lean on earlier ones:

  • Chapters 1 and 2 first. Number sense and fast calculation help in every other chapter.
  • Percentage (3) before Profit, Loss & Discount (7) and Interest (8). Both are percentage questions in disguise.
  • Ratio (4) before Mixture (6), Time & Work (9) and Speed (10). All three run on ratios.
  • Algebra (11) before Geometry (12) and Trigonometry (15). Identities show up in both.
  • Geometry (12) before Mensuration (13 and 14). Area and volume questions often need a geometry fact first.

Short on time? Make sure the four High chapters (7, 12, 13 and 14) and Trigonometry (15) are strong, then cover the rest of the arithmetic block. Statistics and Probability (19 and 20) are only for Tier 2, which comes a few months after Tier 1, so they can wait until Tier 1 is over if you have to choose.

Things to learn by heart

A few tables save seconds on almost every question. Each one is taught properly in its own chapter, but it helps to start learning them now, a few minutes a day:

  • Squares from 1 to 30 and cubes from 1 to 15
  • Fractions as percentages, from 12\frac{1}{2} to 120\frac{1}{20}. For example, 18\frac{1}{8} = 12.5% and 16\frac{1}{6} = 16.67%
  • Common Pythagorean triplets: (3, 4, 5), (5, 12, 13), (8, 15, 17), (7, 24, 25)
  • Values of sin, cos and tan at 0°, 30°, 45°, 60° and 90°

Once these are automatic, a lot of the "shortcuts" in this course stop feeling like tricks and start feeling obvious.