Coding-Decoding and Blood Relations
Overview
Coding-Decoding and Blood Relations are high-scoring Reasoning topics in Railway NTPC and Group D exams. Coding-Decoding tests how letters, numbers, or words are transformed by a fixed rule. Blood Relations tests your ability to trace family connections from given statements. Together, these two topics typically contribute 3–6 questions per exam. Mastering patterns and drawing family trees are the two key skills needed to score full marks here.
Typed Notes
Types of Coding-Decoding
Railway exams use four main types. (1) Letter Coding: CAT → FDW means each letter is shifted +3. Always check if the shift is forward or backward. (2) Number Coding: A=1, B=2 … Z=26; words are coded as sum or product of letter values. (3) Mixed Coding: letters replaced by numbers and vice versa using a key. (4) Conditional/Symbol Coding: specific symbols replace letters based on given conditions (vowels get one symbol, consonants another). Exam Tip: Write the alphabet with position numbers (A=1 to Z=26) on rough paper first — it saves 30 seconds per question.
Decoding the Pattern — Step-by-Step Method
Step 1: Compare the original word and its code letter by letter. Step 2: Find the difference in position values for each letter pair. Step 3: Check if the difference is constant (simple shift) or varies (reverse, alternate shift). Step 4: Apply the same rule to the new word. Example: If DELHI = GHOPL, then D+3=G, E+3=H, L+3=O, H+3=K — wait, H≠K here, so re-check. Always verify all letters before concluding. Memory Hook: 'Same gap, same map' — if the shift is uniform, the rule is a simple Caesar cipher shift.
Blood Relations — Drawing the Family Tree
Always start with the person mentioned first and build downward (children) or upward (parents). Use standard symbols: square for male, circle for female, horizontal line for marriage, vertical line for child. Key exam traps: (1) 'Only son' means no brothers. (2) 'Pointing to a photo' questions — identify the speaker's relation to the photo person. (3) Coded blood relation questions use +, –, ×, ÷ symbols for relations. Example: A + B means A is father of B; A – B means A is mother of B; A × B means A is brother of B; A ÷ B means A is sister of B. Decode the chain step by step.
Common Blood Relation Chains in Railway Papers
Railway NTPC and Group D repeatedly test these chains: (1) 'A is the son of B's father's only daughter' → B's father's only daughter = B's mother → A is B's mother's son → A is B's brother. (2) 'Pointing to a man, a woman says He is the son of my father's only son' → father's only son = the woman's brother → the man is her brother's son = her nephew. Memory Hook: 'Father's only son = the person himself (if no sibling mentioned).' Always re-read whether 'only' applies — it changes the entire answer.
Key Concepts
Revision ke liye ek nazar — exam se pehle yahi padhna hai.
- 01In Letter Coding, each letter is shifted by a fixed number (e.g., A+3=D); always check both forward and backward shifts.
- 02In Number Coding, letters are assigned position values (A=1, Z=26) and then operated upon (add, subtract, multiply).
- 03In Word/Symbol Coding, a whole word is replaced by a code word; find the common word across two statements to crack the code.
- 04In Blood Relations, always draw a family tree diagram; use M/F labels and arrows to avoid confusion between maternal and paternal sides.
- 05Key relation shortcuts: Son's wife = Daughter-in-law; Mother's brother = Maternal Uncle; Father's sister = Paternal Aunt (Bua); Wife's brother = Brother-in-law.
Questions & Solutions
Pehle khud try karo — phir solution kholo. Yahi tariqa topper banata hai.
If in a code language TRAIN is written as WUDLQ, what will PLANE be written as?
If ROAD is coded as 18-15-1-4 and MILK is coded as 13-9-12-11, what is the code for EXAM?
Pointing to a photograph, Ramesh says, 'She is the daughter of my grandfather's only son.' How is the girl related to Ramesh?
A is the mother of B. B is the sister of C. D is the son of C. How is A related to D?
In a code: P % Q means P is father of Q; P $ Q means P is sister of Q; P @ Q means P is mother of Q. If A % B @ C $ D, what is A's relation to D?
Coding-Decoding requires identifying a fixed transformation rule (letter shift, number value, symbol substitution) and applying it consistently. Blood Relations requires drawing a clear family tree and carefully reading relation descriptors. Railway NTPC and Group D papers favor 3-step relation chains and Caesar-cipher letter coding. Practice writing A=1 to Z=26 quickly, and always draw a tree before answering Blood Relation questions to avoid errors.
Chapter-end quiz
4 MCQsOption tap karo — turant pata chalega sahi ya galat, explanation ke saath.
Q1.If BOOK is coded as ERRN, what is the shift applied?
Q2.If MANGO = 13+1+14+7+15 = 50, what is the code for CAT using the same rule?
Q3.A woman says, 'The boy's mother is the only daughter of my mother.' How is the woman related to the boy?
Q4.In a family, X is the brother of Y. Y is the daughter of Z. Z is the father of W. How is X related to W?
Mark karo — dashboard par progress dikhega.