Verbal Reasoning

Analogy means similarity or correspondence between two things. In these questions, the first pair shares a relationship; you must find a second pair with the SAME relationship. Format: A : B :: C : ?

Common relationship types:

• Synonym/Antonym (Big : Large)
• Worker : Tool (Carpenter : Saw)
• Part : Whole (Wheel : Car)
• Cause : Effect (Hard work : Success)
• Object : Function (Pen : Write)
• Animal : Young one (Cow : Calf)

Memory trick: Frame a SENTENCE linking the first pair, e.g. 'A Doctor treats a Patient.' Then apply the SAME sentence to the options: 'A Teacher teaches a ___.' The option that fits perfectly is the answer.

Q: 7 : 56 :: 9 : ?

Step 1: Find the relation between 7 and 56. Try multiplication: 7 x 8 = 56. So the rule could be n x (n+1) = 7 x 8 = 56. Yes!

Step 2: Apply to 9: 9 x (9+1) = 9 x 10 = 90.

Answer: 90.

Tip: Always test common operations in order — multiply, square, cube, add, then combinations like n²+n. Here 7²=49 (no), 7³ too big, so n(n+1) fits. Confirm with the second number before choosing.

Classification questions ask you to be a detective: four or five items are given, and all but one belong to the same secret club. Find the club, and the outsider reveals itself. This lesson covers how to spot the odd one out efficiently.

Definition: A classification (odd-one-out) question presents several items where all except one share a common property; the exception is the answer.

A reliable three-step method

Step idea 1 — Read all options quickly and look for an obvious category: all fruits, all even numbers, all primes, all capital cities.
Step idea 2 — Identify what three (or four) items genuinely have in common.
Step idea 3 — The item that breaks that pattern is the answer.

Common bases of classification

Living vs non-living, even vs odd, prime numbers, perfect squares, vowels vs consonants, geographical groups (capitals vs countries), and word-meaning families. Knowing this menu helps you test the right property fast.

Why it matters: These questions are quick marks if you have a system, but a time-sink if you stare hoping the answer "pops out." A checklist of common bases keeps you fast and confident.

Real-world example: Among "Rose, Lotus, Sunflower, Mango," three are flowers and Mango is a fruit — exactly the "which three are friends?" reasoning you apply on the answer sheet.

Common misconception: Students assume there is only one possible odd one out. Sometimes more than one property could single out a different item, so always pick the most fundamental shared category and confirm the other items all match it.

:::keypoints Key points

• All items share a property except one — find the exception.
• Ask "which three are friends?" and the loner is the answer.
• Test common bases: living/non-living, even/odd, prime, squares, geography.
• Confirm the remaining items truly match before locking your choice.
• Choose the most fundamental shared category if several seem possible.
  :::
  :::recap
• Spot the shared category first, then the outlier.
• Keep a mental menu of common classification bases.
• Always verify the "in-group" before answering.
  :::

Q: Find the odd one: 17, 27, 37, 47

Step 1: Check if they are prime. A prime number has only two factors: 1 and itself.

• 17 = prime (factors 1, 17)
• 27 = 3 x 9 = NOT prime (divisible by 3)
• 37 = prime
• 47 = prime

Step 2: Three of them (17, 37, 47) are prime; 27 is composite.

Answer: 27.

Tip: For number classification, always test primality, even/odd, and perfect squares/cubes. Quick primality check: try dividing by 2, 3, 5, 7.

Number and alphabet series are the easiest 4–5 marks in SSC CHSL Reasoning — if you train your eye to spot patterns in under 20 seconds. The trick is to think like a detective: every series is a hidden rule, and your job is to deduce it from the clues the setter has handed you.

Definition: A series is an ordered sequence of terms (numbers or letters) generated by a fixed rule. The reasoning question shows you the first few terms and asks for the next term, the missing term, or the wrong term.

Definition: A number series uses digits. An alphabet series uses letters of the English alphabet, often converted to positions A=1, B=2, ..., Z=26.

Why "find the differences" beats guessing

When a series is dropped on you, do not stare at the terms in isolation. Write the difference between consecutive terms below the row, as a second row. This single habit unlocks the majority of SSC-level series.

Example: 3, 7, 13, 21, 31, ?

First-row differences: 4, 6, 8, 10. They themselves form an arithmetic progression with common difference 2. So the next difference is 12, and the next term is 31 + 12 = 43. Without the differences, you would have wasted seconds testing wrong hypotheses; with them, the rule is obvious.

If the first-row differences are not constant and do not follow a pattern, take the differences of the differences (second-row differences). When those are constant, the original rule is a quadratic. When even the second row gives you no clue, switch tracks: try ratios (multiplication/division) or check for squares and cubes.

The five common number-series patterns

Memorise these as your toolkit. Most SSC, RRB, and bank-exam series fall into one of these buckets.

1. Addition or subtraction (arithmetic). The differences are constant: +2, +2, +2, ... or −3, −3, −3, ...

Example: 2, 5, 8, 11, 14, ... (each +3).

2. Multiplication or division (geometric). Each term equals the previous one multiplied by a fixed ratio.

Example: 3, 6, 12, 24, 48, ... (each x2).

3. Squares or cubes. Each term is n^2 or n^3 for n = 1, 2, 3, ...

Squares: 1, 4, 9, 16, 25, 36, 49, 64, 81, 100, 121, 144 — memorise up to 15^2 = 225.
Cubes: 1, 8, 27, 64, 125, 216 — memorise up to 10^3 = 1000.
Also recognise (n^2 − 1), (n^2 + 1), (n^2 + n) variants, which are SSC favourites.

4. Mixed alternating rules. Two interleaved series, one with +k and another with xm. Always check whether terms at odd positions and even positions follow separate rules.

Example: 4, 9, 6, 11, 8, 13, ?
Odd positions: 4, 6, 8, ... (next is 10).
Even positions: 9, 11, 13, ... (next is 15).
So the missing term is 10.

5. Difference of differences (second-level). When the gaps themselves grow, peel one more layer. Example shown above (3, 7, 13, 21, 31, 43).

Alphabet series — the EJOTY anchor

Converting letters to position numbers is the key move. Whenever you see a letter, mentally write its position. To do this fast, do not count from A every time — anchor to the EJOTY ladder:

E = 5, J = 10, O = 15, T = 20, Y = 25.

If you see the letter R, you know T = 20 and R is two before T, so R = 18. If you see L, you know J = 10 and L is two after J, so L = 12. This trick alone saves 5–8 seconds per question.

Example: D, G, J, M, P, ?
Positions: 4, 7, 10, 13, 16. Difference is +3 each time. Next position is 19, which is one before T = 20, so the letter is S.

Reverse counting: sometimes a series counts backwards. Y, U, Q, M, I, ?
Positions: 25, 21, 17, 13, 9. Difference is −4 each time. Next is 5, which is E.

Definition: A letter-and-number combined series alternates between letters and numerals. Treat the letters and numbers as two separate sub-series, each with its own rule. Solve them independently.

Why it matters

Why it matters: SSC CHSL Tier-I Reasoning typically has 3–5 number-or-alphabet series questions out of 25, and the cut-off is brutal. These are the fastest marks on the paper — a strong candidate solves each in 15–25 seconds and saves time for Quant. If you misallocate even 30 seconds extra here, you have probably lost a Quant question elsewhere.

Real-world example: Series-style logic appears in real coding-decoding puzzles used by banks for OTP generation and account validation. The Aadhaar verification last-digit check, for example, is a checksum computed from a positional weighting rule — not very different in spirit from "convert letters to positions and find the rule."

A worked example you can drill

Question: Find the missing term — 5, 11, 23, 47, ?, 191.

Solution:
Step 1: Write the differences: 6, 12, 24, ... These double each time.
Step 2: Notice another rule: each term is roughly double the previous + 1. Check: 5x2+1 = 11, 11x2+1 = 23, 23x2+1 = 47.
Step 3: Apply the rule to find the next term: 47x2+1 = 95.
Step 4: Verify with the term after: 95x2+1 = 191. Matches the given last term.
Conclusion: The missing term is 95.

Common misconceptions

Common misconception: "If two consecutive differences match a pattern, the rule is found." Not always. Test the rule on at least three pairs of consecutive terms before committing. A series like 2, 4, 8, 14, 22 has first differences 2, 4, 6, 8 — an AP — but the underlying rule is quadratic. Stop too early and you will pick the wrong answer.

Common misconception: "Letters always count forward." They do not. Trained setters love reverse-direction series (Y, U, Q, M, ...) and skipping series (A, C, F, J, ...). Always check both directions.

Common misconception: "Mixed series look complicated." They look complex because two simple rules are interleaved. Split into odd-position and even-position sub-series and the complexity vanishes.

:::compare

Pattern type	First-difference behaviour	Tell-tale signal
Arithmetic (+/−)	Constant	Same gap throughout
Geometric (x/÷)	Increases multiplicatively	Differences grow much faster than linearly
Squares / cubes	Match 1, 4, 9, 16 or 1, 8, 27	Sudden jumps that "remind you" of square table
Mixed alternating	Two interleaved patterns	Look at odd and even terms separately
Second-level differences	First differences also follow a rule	Gaps grow but in a tidy pattern
:::

:::keypoints

• Always write the difference row before guessing the rule.
• Memorise squares up to 15^2 = 225 and cubes up to 10^3 = 1000.
• Use the EJOTY anchor (E=5, J=10, O=15, T=20, Y=25) for instant letter–number conversion.
• For mixed series, split into odd-position and even-position sub-series.
• If first differences fail, take second-level differences.
• Test your hypothesised rule on at least three pairs before locking in an answer.
• Alphabet series can run backwards — always check direction.
  :::

:::memory
EJOTY — five anchors at gaps of 5. Whisper "Every Junior Officer Tries Yoga" to lock the order: E-J-O-T-Y at positions 5-10-15-20-25.
:::

:::recap

• A series is a hidden rule; differences and ratios are your clues.
• Five core patterns: AP, GP, squares/cubes, mixed alternating, second-level differences.
• EJOTY makes alphabet-to-number conversion instant.
• Drill 20+ varied series per week and the SSC reasoning cut-off becomes much easier to clear.
  :::

Useful tools:

1. EJOTY positions: A=1, E=5, J=10, O=15, T=20, Y=25, Z=26. To find letter at position 18: it is between O(15) and T(20), count O,P,Q,R = 18, so R.

2. Common number rules to test in order:
   +constant -> +growing -> x constant -> squares -> cubes -> alternate two rules.

Worked example: 3, 6, 11, 18, 27, ?
Differences: 3, 5, 7, 9 (increasing by 2). Next difference = 11. So 27 + 11 = 38.
Answer: 38.

Tip: For two-step alternating series like 2, 6, 4, 12, 8 ... separate odd and even positions and solve each chain independently.

Every SSC CHSL reasoning paper has a coding-decoding question. The chapter looks intimidating only until you see the four standard patterns. After that, it becomes one of the most rewarding sections in the paper.

Definition: Coding is the process of converting a word or message into a secret form by following a rule. Decoding is the reverse — recovering the original word from its coded form.

Definition: The rule is the heart of every coding question. The exam never asks you to invent a rule; it shows you one example, and your job is to find the rule and apply it to a new word.

The four classical patterns

In SSC CHSL, the General Intelligence section serves coding-decoding questions that fall into four well-known patterns. Memorising the patterns once gives you a lifetime advantage.

Letter shifting moves every letter forward or backward by a fixed number in the English alphabet. If CAT becomes DBU, look closely: C→D is +1, A→B is +1, T→U is +1. The shift is constant (+1) and the rule is clear. Some questions shift backwards: CAT → BZS (each −1). Some are larger shifts: CAT → HFY (+5). The skill is identifying the gap quickly.

Reverse coding writes the word backwards. CAT → TAC. SCHOOL → LOOHCS. There is no math, no shift — just a mirror. It is the easiest of the four families, and it shows up often in SSC CHSL because it tests whether you read the example carefully or assume a shift.

Number coding replaces each letter by its position number in the English alphabet: A=1, B=2, C=3, … Z=26. CAB becomes 3, 1, 2. BAD becomes 2, 1, 4. The reverse scheme (A=26, B=25, … Z=1) is also common — and that's a popular trap. Always verify which scheme the example uses before you decode the target.

Substitution is the trick family. Whole words get redefined: "If apple is called mango, mango is called banana, banana is called orange, then what do monkeys love to eat?" The answer is banana, because the original food mango has been renamed banana in this puzzle. There is no calculation — just disciplined reading.

Why this chapter is a scoring goldmine

SSC CHSL Tier-1 has 25 reasoning questions worth 50 marks. Coding-decoding alone usually contributes 2-4 marks. These marks are entirely about pattern-spotting; they need no advanced math or vocabulary. A candidate who has practised 50-60 coding questions in their lifetime will recognise the family within 5 seconds and solve within another 20.

The hidden benefit is time saved. If coding sets cost you only 25 seconds each, you have spare minutes to spend on tougher Series and Puzzle sets. That redistribution can lift your reasoning score by 3-5 marks overall, which often makes the difference between a Tier-2 callup and a near miss.

The position-number rough line

Before you start any coding section, mentally scribble A=1, B=2, …, Z=26 across a rough line in your notebook. It takes 10 seconds. Combined with the EJOTY anchor (E=5, J=10, O=15, T=20, Y=25), counting any letter's position becomes near-instant. For example, if you need P, jump to O=15 and add 1 → P=16. If you need M, jump to J=10 and add 3 → M=13.

The same trick works backwards. To find Z=26, V=22, S=19 in the reverse scheme, just subtract from 27: A=27−1=26 reverse, B=27−2=25 reverse, and so on.

Real-world example: Indian Railways uses station codes like NDLS (New Delhi) and CSTM (Chhatrapati Shivaji Terminus). These are not strict letter shifts, but the principle — a short coded form representing a longer name — is the same substitution logic that coding-decoding uses in your exam. The mental habit of "decode the rule, then apply it" is the same one a station master uses every morning.

Question: If WHITE is coded as XIJUF, find the code for BLACK.
Solution:
Step 1: Compare W→X (+1), H→I (+1), I→J (+1), T→U (+1), E→F (+1).
Step 2: The shift is constant at +1.
Step 3: Apply to BLACK — B→C, L→M, A→B, C→D, K→L.
Conclusion: BLACK is coded as CMBDL.

Common misconception: "Reverse coding and letter shifting look similar — I'll guess." They are completely different families. Reverse coding produces a word the same length, with the letters in the opposite order; letter shifting produces a word the same length but with each letter advanced or retreated. If you can't tell them apart, count the matching letters position-by-position. If position 1 of the code equals the last letter of the original, it's a reverse code. If position 1 of the code is one or two letters away from the first letter of the original, it's a shift. A 5-second check beats a guessed answer.

A four-step decoder for any question

1. Read both the example and the target word slowly.
2. Compare lengths. Same length → either shift, reverse, or number coding. Different length → almost always substitution or number coding.
3. Test for reverse. Check if the code reads as the original spelled backwards. If yes, you're done.
4. Test for shift. Find the gap for each letter. If constant, apply that gap to the target. If not constant, suspect an alternating shift.

Most SSC questions resolve at step 3 or step 4. This routine takes well under a minute.

:::compare

Pattern	Example	Rule	Difficulty
Letter shift (+1)	CAT → DBU	Each letter +1	Easy
Reverse coding	CAT → TAC	Spell backwards	Easiest
Number coding (A=1)	CAB → 3,1,2	Position number	Easy
Number coding (A=26)	CAB → 24,26,25	Reverse position	Medium
Substitution	"apple = mango"	Word swap	Easy if read carefully
:::

:::keypoints

• Coding-decoding has four classical families: shift, reverse, number, substitution.
• The rule is given to you — never invent one.
• Write A=1 to Z=26 on a rough line before starting the section.
• Memorise EJOTY (E=5, J=10, O=15, T=20, Y=25) as positional anchors.
• Always verify the rule against every letter in the example before applying.
• Reverse coding produces same-length words read backwards — easy to miss if you assume a shift.
• Number coding can use A=1 OR A=26; check the example carefully.
• Substitution needs no math, only disciplined reading.
  :::

:::memory
"SHIFT, MIRROR, NUMBER, SWAP" — the four families of coding-decoding. If you remember these four words in order, you can classify any SSC CHSL coding question in under five seconds.
:::

:::recap

• Identify the family first; apply the rule second.
• Letter shift, reverse coding, number coding and substitution cover almost every SSC CHSL coding question.
• EJOTY and the A=1 line are non-negotiable speed tools.
• A four-step decoder (read, compare lengths, test reverse, test shift) cracks any standard set in under a minute.
  :::

Q: If CAT is coded as ECV, how is DOG coded?

Step 1: Compare CAT with ECV.

• C(3) -> E(5): +2
• A(1) -> C(3): +2
• T(20) -> V(22): +2
  Rule: each letter moves +2.

Step 2: Apply +2 to DOG.

• D(4) -> F(6)
• O(15) -> Q(17)
• G(7) -> I(9)

Answer: FQI.

Tip: If a letter goes past Z, wrap around to A (Z+1 = A). Always verify the SAME shift works for every letter of the example before applying it.