Coding-decoding

Verbal reasoning is perhaps the most trainable skill in any competitive exam — not because it is easy, but because every question type reduces to a small set of disciplined rules, and once those rules are internalised, you never have to guess.

Definition: Verbal reasoning is logical inference conducted through language: you evaluate relationships between words, assess arguments stated in sentences, and draw conclusions from passages — all without relying on outside knowledge. The golden rule: stay strictly inside the information given; outside knowledge is always a trap.

1. Verbal analogy — find the relationship type first

An analogy question (A : B :: C : ?) tests whether you can identify the precise relationship between A and B, then find the D that has the same relationship to C. The relationship type matters more than the subject.

Catalogue of common relationship types:

Process: (1) State the relationship in words ("a Doctor uses a Stethoscope as a tool"); (2) Apply that sentence to C ("a Pilot uses a ___"); (3) Pick D that fits the same sentence ("Cockpit" or "Controls").

Watch for reversed relationships: if the question gives Tool : Worker (Saw : Carpenter), your answer must also be Tool : Worker (Stethoscope : Doctor), not the other way.

2. Verbal classification — what makes the others the same?

The "odd one out" question gives four or five items that share a property, with one intruder that lacks it. Your job is to identify the common property that defines the group, then find the one that doesn't fit.

Strategy: don't look for what's different about the odd one first — look for what's the same about the group.

Examples:

• Lion, Tiger, Leopard, Cat: the first three are large wild cats; a cat is a domestic animal.
• Mars, Jupiter, Saturn, Sun: the first three are planets; the Sun is a star.
• January, March, May, June: the first three have 31 days; June has 30.

Watch for multiple possible groupings — sometimes the examiner intends a specific property that isn't the most obvious one. Read the question phrasing for hints; if the wording says "does not belong to the group," find the property that defines the largest subset.

3. Syllogism

Syllogism questions give two (or more) statements and ask which conclusions follow logically. The gold-standard technique is Venn diagrams — draw circles for each category and shade possible overlaps.

Core forms:

• "All A are B" → circle A sits entirely inside circle B.
• "No A is B" → circles A and B are completely separate.
• "Some A are B" → circles A and B partially overlap.
• "Some A are not B" → part of circle A is outside circle B.

Standard valid patterns:

• All A are B + All B are C → All A are C (universal positive chain).
• All A are B + No B is C → No A is C.
• All A are B + Some B are C → only Some A may be C (not "all"; not "no") — Possible conclusion, not definite.

Never assume from "some": "Some cats are black" does not mean "Some black things are cats" is definitely false, but it cannot be stated as "All cats are black."

Possibility conclusions: when the examiner asks "which conclusion is a possibility?" rather than a certainty, you need to check whether the Venn diagram can be drawn so as to make the conclusion true (not necessarily must be true).

4. Statement and assumption

An assumption is an unstated premise that is necessary for a statement to make logical sense. The test: if the assumption were false, would the statement become meaningless or self-contradictory?

Question:
Statement: "The government must improve roads to reduce accidents."
Which assumption is implicit?
(I) Bad roads cause accidents.
(II) Building roads is expensive.

Analysis:

• (I) If bad roads did NOT cause accidents, improving them would not reduce accidents — the statement would be nonsensical. So (I) is a necessary underlying premise → implicit assumption ✓
• (II) The statement is still meaningful even if road construction were free. Cost is irrelevant to the logic → not implicit ✗

Checklist for implicit assumptions:

1. Is the assumption necessary (the statement breaks without it)?
2. Is it too obvious / a universal truth? (Usually implicit — e.g., "Fire is hot" doesn't need to be stated explicitly.)
3. Is it a separate fact that needs independent proof? (Then it's NOT an assumption.)

Common trap: "An advertisement for coaching classes assumes coaching helps you pass." That is exactly what the ad is claiming — it's too close to the statement itself. A genuine assumption is one step behind the claim.

5. Statement and conclusion

A conclusion follows logically from the statement if, and only if, it is forced by the statement — you cannot deny the conclusion without contradicting the statement.

Question:
Statement: "Most students who study late at night perform poorly in exams."
Conclusion I: Students should avoid late-night study.
Conclusion II: Sleep is essential for learning.

Analysis:

• Conclusion I: "Most perform poorly" → "should avoid" is a practical recommendation that is a reasonable inference from the data. Many exams accept this as following.
• Conclusion II: Sleep being essential is a general scientific claim; the statement is about late-night study and performance — you cannot deduce the universality of sleep from this one observation. Does not follow ✗

Test for "follows": can you imagine a world in which the statement is true but the conclusion is false? If yes → conclusion does not follow.

Absolute words in conclusions: Conclusions with "always," "never," "all," "none," or "must" are almost always wrong when the statement contains "most," "many," "sometimes" or "usually." Match the quantifiers.

6. Course of action

Two or more proposed responses to a problem situation are given. You must judge whether each is "strong" (appropriate, directly addresses the problem, feasible) or "weak" (impractical, irrelevant, excessive).

Statement: "Many farmers in Region X are committing suicide due to crop failure."

Course I: Government should provide crop insurance to affected farmers.
Course II: Farmers should be asked to leave farming permanently.

Analysis:

• Course I: Directly tackles the financial devastation of crop failure; feasible through an existing policy framework. → Strong ✓
• Course II: Displacing an entire farming community is neither practical nor proportionate; it doesn't solve the crisis and creates new social problems. → Weak ✗

Rules for "strong" actions:

1. Directly targets the stated problem (not a proxy or side effect).
2. Practically feasible (legal, financially achievable, socially acceptable).
3. Proportionate to the scale of the problem.
4. Does not create new significant problems of its own.

7. Cause and effect

Two statements A and B are given; determine the relationship:

• A is the cause, B is the effect.
• B is the cause, A is the effect.
• Both are effects of a common, unstated cause.
• Both are independent coincidences.

Example:
A: "There has been heavy rain in the city for three days."
B: "Local rivers have flooded."

Clearly A causes B; flooding follows heavy rain. The reverse (flooding caused rain) is physically impossible.

Tricky pair (common cause):
A: "The price of onions has skyrocketed."
B: "Onion exports have been banned."

Here neither causes the other — both are effects of a single cause: a bad monsoon reducing supply. Look for a plausible third factor.

Test for independence: do A and B occur in different domains with no plausible mechanism linking them? Then they are likely independent.

8. Decision making (situational judgment)

Used heavily in CSAT, banking PO and GMAT reasoning. A real-world scenario is presented and you must choose the best response.

Framework: legal → ethical → practical → constructive. A good decision violates none of these; an excellent one is constructive (creates positive value, not just prevents harm).

Example scenario: You are a manager. Your honest subordinate makes an error costing the company ₹1 lakh.

• Option A: Fire him immediately.
• Option B: Reprimand formally and use it as a training case.
• Option C: Ignore it to avoid conflict.
• Option D: Escalate to senior management to handle.

Best: Option B. Firing is disproportionate for an honest mistake; ignoring it sets a bad precedent; escalating shifts accountability unnecessarily. A proportionate reprimand plus learning preserves the relationship, deters future errors and builds team culture.

Why it matters: Verbal reasoning constitutes 20–40 % of the reasoning section in RRB (both NTPC and Group D), SSC CGL/CHSL and banking exams. Because the answers depend on rules (not memorised facts), a student who masters the disciplined framework can score perfectly on this section regardless of the topic of the statements.

Real-world example: Judges and administrators use verbal-reasoning skills professionally. A magistrate reading a petition must separate the implicit assumption (the petitioner assumes the law applies to their case) from the explicit claim, and must judge whether a proposed action (issuing a stay order) is proportionate and feasible. Statement-assumption and course-of-action skills are not abstract exam techniques — they are the formal structure of careful institutional thinking.

Common misconception: The most damaging habit in verbal reasoning is importing real-world general knowledge into conclusions. Students read "Most engineers are well-paid" and immediately select "Therefore all technical professionals are wealthy" because they believe it to be broadly true. In the exam, a conclusion must follow from the given statement, not from the world. A conclusion that happens to be true in reality but isn't forced by the statement is marked wrong. Train yourself to ask: "Does this follow from this statement, ignoring everything I know from outside?"

Quick-revision notes for Coding-decoding — the must-know points for SSC CGL Tier-I/II.

• Coding-decoding hides a message using a fixed rule; decode by finding the letter/number shift or pattern the setter used.
• Letter-shift coding: each letter moves a constant number of places forward/backward (e.g. +1 makes CAT→DBU). Fix the alphabet positions A=1…Z=26.
• Number coding: letters replaced by their position values, sums, or products of positions (e.g. sum of positional values of the word).
• Substitution coding: whole words swapped for other words (e.g. "sky is blue" → "blue is red"); track word-to-word mapping.
• Symbol/mixed coding and conditional coding (rules given in a table) are common in Tier-I; apply the given conditions strictly, in order.
• Reverse-order and interleaving tricks: alternate letters coded differently, or the word written backwards then shifted — check first and last letters to spot it.

Cover the answer, recall, then check. 6 cards on the must-know Coding-decoding facts for SSC CGL.

Q1. If in a code CAT is written as DBU, how is DOG written?
A1. EPH — each letter moves +1 (C→D, A→B, T→U), so D→E, O→P, G→H.

Q2. What is the positional value of the letter M and its "opposite" letter?
A2. M = 13; its opposite (from the other end, 27−position) is N (27−13 = 14).

Q3. How do you decode a word coded by the sum of letter positions?
A3. Add the alphabetical positions of all letters (A=1…Z=26); the code equals that total — e.g. CAB = 3+1+2 = 6.

Q4. In substitution coding "green means hot", if asked the colour of fire, what do you answer?
A4. Whatever word substitutes for the true answer — reply with the coded word, not the real one.

Q5. Quickest first check in any letter-coding question?
A5. Compare the first letters of word and code to find the shift, then verify it holds for the remaining letters.

Q6. What is EJK code type if letters jump +5 each time from ZEF?
A6. Backward/forward constant shift — ZEF+5 = EJK (Z→E wrapping, E→J, F→K), a classic cyclic shift.

Worked Example

Problem: In a certain code language, "READ" is written as "TGCF". Following the same rule, how is the word "WRITE" written in that code?

Solution:
Compare each letter of READ with its code TGCF and find the shift.
R (18) → T (20): +2
E (5) → G (7): +2
A (1) → C (3): +2
D (4) → F (6): +2
Every letter moves 2 places forward in the alphabet. Apply the same +2 shift to WRITE:
W (23) → Y (25)
R (18) → T (20)
I (9) → K (11)
T (20) → V (22)
E (5) → G (7)

Answer: WRITE is coded as YTKVG.