In this guide
Of the four SSC CHSL subjects, reasoning rewards practice most directly. The question types are few and they repeat. Once you have solved a hundred coding–decoding questions, the hundred-and-first takes seconds, because you are recognising a pattern rather than discovering one. Maths needs concepts and English builds slowly through reading, but reasoning mostly needs volume and a method for each type.
That makes it the best section to lift your score quickly. Six focused weeks, one type at a time, is enough to cover every type and build real speed.
Weightage
| Stage | Questions | Marks | Time |
|---|---|---|---|
| Tier 1 | 25 | 50 | 15 minutes (sectional) |
| Tier 2, Section I | 30 | 90 | Shares one hour with maths |
In Tier 1 you get about 36 seconds per question. In Tier 2 a wrong answer costs a full mark, so accuracy matters more than speed. A candidate who can finish reasoning in 25–30 minutes in Tier 2 leaves maths the time it needs.
Question types and the core method
| Type | What it tests | Core method |
|---|---|---|
| Analogy, classification | Spotting a relationship | State the rule in a sentence and test it on every option |
| Number and letter series | Patterns | Differences first, then squares, cubes and alternate terms |
| Alphabet test, coding–decoding | Letter positions | Write A1 to Z26; check shifts, reversals, opposite letters |
| Blood relations | Family logic | Draw a tree with genders marked only when stated |
| Directions | Spatial tracking | Draw the path; use Pythagoras for the final distance |
| Ranking, order | Counting | Total = rank from top + rank from bottom − 1 |
| Syllogism, Venn diagrams | Set logic | Draw the least-overlap diagram |
| Mathematical operations | Symbol substitution | Replace symbols, then apply BODMAS |
| Clocks, calendars | Rules | Mirror rule; odd days |
| Mirror, water, paper folding, figures | Visual logic | Track one element at a time |
A six-week plan
| Week | Topics |
|---|---|
| 1 | Analogy, classification, number series |
| 2 | Alphabet test, letter series, coding–decoding |
| 3 | Blood relations, directions, ranking |
| 4 | Syllogism, Venn diagrams, mathematical operations |
| 5 | Mirror and water images, paper folding, embedded figures, figure series, counting figures |
| 6 | Clocks, calendars, seating arrangement; mixed sectional tests |
A daily routine (45 minutes)
- 25 minutes: 30 questions on the current week's topics.
- 10 minutes: 10 mixed questions from earlier weeks, so older topics stay fresh.
- 10 minutes: review every mistake and write the reason in an error log.
The review step is the one most people skip, and it matters most. A mistake you understand is unlikely to repeat; a mistake you ignore usually does.
Speed habits, and why they work
- Write the alphabet with positions (A1 … Z26) on your rough sheet at the start. Use EJOTY (5, 10, 15, 20, 25) to find any position in two steps. Opposite letters add to 27 (A–Z, B–Y, M–N), because a letter n places from the start is n places from the end.
- Draw family trees and direction paths. Holding four relationships in your head is where errors creep in.
- Test the options in series, analogy and coding. Checking is faster than generating.
- In figure questions, track one element at a time, for example the dot first, then the arrow. Most figure series change two or three elements independently.
- Learn the fixed rules: a clock's mirror image is 11:60 minus the time; an ordinary year has 1 odd day and a leap year 2.
Six worked questions
Q1. Find the next term: 3, 8, 15, 24, 35, ?
Differences are 5, 7, 9, 11, so the next is 13 and the term is 48. Equivalently, the terms are n² − 1 for n = 2 to 7. Answer: 48.
Q2. If COLD is coded as DPME, how is WARM coded?
Each letter moves one place forward. W → X, A → B, R → S, M → N. Answer: XBSN.
Q3. A is B's brother. C is A's mother. D is C's father. How is D related to B?
C is the mother of A and B. D is C's father, so D is B's maternal grandfather. Answer: grandfather. The genders come from "brother", "mother" and "father" in the question; B's gender is not given and is not needed.
Q4. A person walks 5 km north, turns right and walks 3 km, then turns right and walks 9 km. How far and in which direction are they from the start?
Draw it: north 5, east 3, south 9. They end 3 km east and 4 km south of the start. Distance = √(9 + 16) = 5 km, south-east.
Q5. A clock shows 4:20. What time does its mirror image show?
11:60 − 4:20 = 7:40.
Q6. 1 January 2025 was a Wednesday. What day was 1 January 2026?
2025 is not a leap year, so it has 365 days, which is 52 weeks and 1 odd day. Answer: Thursday.
Common traps
| Trap | Fix |
|---|---|
| Accepting a series pattern that fits only two terms | Check it on every term |
| Assuming gender from a name | Use only stated genders |
| Confusing mirror and water images | Mirror flips left–right; water flips top–bottom |
| Treating every century year as a leap year | 1900 was not; 2000 was |
| Counting a rank twice | Total = top rank + bottom rank − 1 |
Practice
- Find the next term: 2, 6, 12, 20, 30, ?
- If DOG = 26 (4 + 15 + 7), what is CAT?
- Find the odd one out: 64, 81, 100, 120, 144.
- What time does the mirror image of a clock showing 3:15 show?
- A person walks 10 m east, turns left and walks 6 m, then turns left and walks 10 m. Where are they relative to the start?
- If MANGO is written as OCPIQ, how is APPLE written?
- A candidate is 12th from the top and 18th from the bottom of a list. How many candidates are on the list?
- 15 August of a year is a Friday. What day is 15 September of the same year?
Answers:
- 42. Terms are n(n + 1): 6 × 7 = 42. Differences 4, 6, 8, 10, 12 confirm it.
- 24. 3 + 1 + 20.
- 120. The others are perfect squares (8², 9², 10², 12²).
- 8:45. 11:60 − 3:15.
- 6 m north. East 10, north 6, west 10 leaves only the 6 m north.
- CRRNG. Each letter moves two places forward, as M → O and A → C show.
- 29. 12 + 18 − 1.
- Monday. August has 31 days, so 15 September is 31 days later: 4 weeks and 3 odd days after Friday.
A self-check after six weeks
- I can solve analogy and series questions in under 30 seconds each.
- I draw a diagram for every blood relation and direction question.
- I know the mirror-clock rule and the odd-days rule without looking.
- My error log has a written reason for every mistake from the last two weeks.
- I have taken at least six timed reasoning sectionals.
Start with analogies, then work through coding–decoding and blood relations in the order of the plan above.
A note on dates and numbers. Exam patterns, vacancies and schedules change from year to year. Always confirm the current details in the latest notification on the Staff Selection Commission website .
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