Coding-Decoding: Full-Length Notes (Letter Shifting, Symbol Coding, Number Coding)
Coding-Decoding: Full-Length Notes
(Letter Shifting, Symbol Coding, Number Coding)
Introduction to Coding-Decoding
Coding-Decoding is a fundamental topic in logical reasoning and aptitude tests, especially for competitive exams. It assesses your ability to decipher patterns and relationships between letters, numbers, or symbols and apply the same logic to decode or encode new information1235. Mastery of this topic requires understanding the types of coding, recognizing patterns, and practicing a variety of question formats.
Types of Coding-Decoding
1. Letter Shifting (Letter Coding)
Definition:
In letter shifting, each letter in a word is replaced by another letter according to a specific rule. The rule could involve shifting letters forward or backward in the alphabet, reversing the order, or substituting with corresponding letters1256.
Common Patterns:
Forward Shifting: Each letter is replaced by the next letter (A→B, B→C, etc.)
Backward Shifting: Each letter is replaced by the previous letter (B→A, C→B, etc.)
Fixed Shifting: Shift by a fixed number of positions (e.g., +2: A→C, B→D)
Reverse Order: The word is written in reverse (CAT → TAC)
Position Value Substitution: Replace each letter with its position in the alphabet (A=1, B=2, ..., Z=26)
Interchanging Letters: Swap positions of specific letters.
Examples:
Example 1: If "DELHI" is coded as "EDMGJ", how is "NEPAL" coded?
Explanation: Each letter is shifted by a certain rule. D→E (+1), E→D (-1), L→M (+1), H→G (-1), I→J (+1). Apply the same pattern to NEPAL.
Example 2: If "CAT" is coded as "DBU", what is the code for "DOG"?
Explanation: C→D (+1), A→B (+1), T→U (+1). So, D→E, O→P, G→H. Code: "EPH".
2. Symbol Coding
Definition:
In symbol coding, words or letters are replaced with symbols or a combination of symbols, letters, or numbers. The logic may involve direct substitution, pattern recognition, or matching codes across statements1235.
Common Patterns:
Direct Substitution: Each word/letter is replaced with a specific symbol.
Mixed Coding: Sentences are coded with a mix of symbols, and common words have the same code across different statements.
Chinese Coding: Multiple statements use the same words in different orders, helping to deduce the code for each word.
Examples:
Example 1:
"Balloons are blue" is coded as "834",
"Rainbow in sky" is coded as "723",
"Box is heavy" is coded as "325".
What is the code for "is"?
Explanation: "is" appears in "Box is heavy" (325) and "Carpet is beautiful" (629). Find the common code.
Example 2:
If "Park is School" is coded as "nup ace ybx", and "School is fun" is coded as "ybx ace vcl", what is the code for "School"?
Explanation: "School" appears in both; the common code is "ybx".
3. Number Coding
Definition:
In number coding, words or letters are represented by numbers, often based on their position in the alphabet, sum of values, or a specific numerical pattern1257.
Common Patterns:
Alphabet Position Coding: Each letter is replaced by its alphabetical position (A=1, B=2, ..., Z=26).
Sum Coding: The code is the sum of the alphabetical values of all letters in the word.
Complex Pattern: Numbers may be assigned based on a hidden rule (e.g., reverse order, alternate addition/subtraction).
Examples:
Example 1: If "CHAIR" is coded as "12345" and "RENT" as "5678", what is the code for "REAR"?
Explanation: Assign numbers to each letter as per the pattern in the question.
Example 2: If "MANGO" is coded as "50" (M=13, A=1, N=14, G=7, O=15; 13+1+14+7+15=50), what is the code for "APPLE"?
Explanation: A=1, P=16, P=16, L=12, E=5; 1+16+16+12+5=50.
Advanced Coding-Decoding Types
Substitution Coding: Words are replaced with other words (e.g., "Blue" stands for "Red").
Conditional Coding: Codes are assigned based on given conditions or rules.
LSN Coding: Words are coded using a mix of letters, symbols, and numbers2.
Tips and Tricks for Coding-Decoding
EJOTY Rule: E=5, J=10, O=15, T=20, Y=25 helps quickly find letter positions1.
Check for Opposite Letters: Sometimes, coding uses opposite letters (A↔Z, B↔Y, etc.).
Analyze for Patterns: Look for consistent shifts, reversals, or substitutions.
Use Elimination: In mixed or Chinese coding, eliminate options by matching common words and codes.
Practice: Regular practice with all types of coding-decoding questions is crucial for speed and accuracy12356.
Practice Questions
Letter Shifting:
If "BIRD" is coded as "CJSE", how is "FISH" coded?
If "APPLE" is coded as "BQQMF", how is "MANGO" coded?
If "CAT" is coded as "DBU", how is "DOG" coded?
Symbol Coding:
4. "Sky is blue" is coded as "@ # $". "Blue is deep" is coded as "$ # %". What is the code for "is"?
5. "Sun rises in east" is coded as "α β γ δ". "Moon rises in west" is coded as "ε β γ ζ". What is the code for "rises"?
Number Coding:
6. If "TREE" is coded as "20 18 5 5", how is "LEAF" coded?
7. If "MANGO" is coded as "50", how is "BANANA" coded?
8. If "CHAIR" is coded as "3 8 1 9 18", how is "TABLE" coded?
(For more practice questions and solutions, see the resources linked in the search results.)
Conclusion
Coding-Decoding is a reasoning skill that combines logic, pattern recognition, and analytical thinking. Master letter shifting, symbol coding, and number coding by understanding the rules, practicing different question types, and applying systematic approaches to decode or encode information efficiently123567.
Letter Shifting / Letter Coding (1–40)
If CAT is coded as DBU, how is DOG coded?
Answer: EPH
Explanation: Each letter shifted +1.
If BALL is coded as CBMM, how is CALL coded?
Answer: DBMM
Explanation: Each letter shifted +1.
If MANGO is coded as NBOHP, how is GRAPE coded?
Answer: HSBQF
Explanation: Each letter shifted +1.
If FISH is coded as GJTI, how is BIRD coded?
Answer: CJSE
Explanation: Each letter shifted +1.
If TREE is coded as USFF, how is LEAF coded?
Answer: MFBG
Explanation: Each letter shifted +1.
If CAT is coded as XZG, how is DOG coded?
Answer: ALD
Explanation: Each letter shifted -3.
If ROSE is coded as TQUG, how is LILY coded?
Answer: NKNA
Explanation: Each letter shifted +2.
If BOOK is coded as DQQL, how is PAGE coded?
Answer: RCIG
Explanation: Each letter shifted +2.
If SUM is coded as TVN, how is WIN coded?
Answer: XJO
Explanation: Each letter shifted +1.
If KING is coded as MJPI, how is QUEEN coded?
Answer: TXHHQ
Explanation: Each letter shifted +3.
If DOG is coded as FQI, how is CAT coded?
Answer: ECV
Explanation: Each letter shifted +25.
If PEN is coded as QFO, how is INK coded?
Answer: JOL
Explanation: Each letter shifted +1.
If LEMON is coded as NGPQP, how is ORANGE coded?
Answer: QTCPIG
Explanation: Each letter shifted +2.
If STAR is coded as TUBS, how is MOON coded?
Answer: NPPQ
Explanation: Each letter shifted +1.
If TABLE is coded as UBCMF, how is CHAIR coded?
Answer: DIBJS
Explanation: Each letter shifted +1.
If BOY is coded as DQA, how is GIRL coded?
Answer: IKTN
Explanation: Each letter shifted +2.
If HAT is coded as IBV, how is CAP coded?
Answer: DBQ
Explanation: Each letter shifted +1.
If CAT is coded as GEX, how is DOG coded?
Answer: HQJ
Explanation: Each letter shifted +4.
If LAMP is coded as NCOQ, how is BULB coded?
Answer: DWND
Explanation: Each letter shifted +2.
If TREE is coded as VTKG, how is LEAF coded?
Answer: NGCH
Explanation: Each letter shifted +2.
If MOUSE is coded as NPTUF, how is RAT coded?
Answer: SBU
Explanation: Each letter shifted +1.
If CAT is coded as ZXR, how is DOG coded?
Answer: ALD
Explanation: Each letter shifted -3.
If RED is coded as UHG, how is BLUE coded?
Answer: EOXH
Explanation: Each letter shifted +3.
If TEA is coded as UFB, how is COFFEE coded?
Answer: DPGGFF
Explanation: Each letter shifted +1.
If LION is coded as MJPO, how is TIGER coded?
Answer: UJHFS
Explanation: Each letter shifted +1.
If ZEBRA is coded as AFCSB, how is HORSE coded?
Answer: IPSUF
Explanation: Each letter shifted +1.
If BIRD is coded as DJTF, how is FISH coded?
Answer: HKUJ
Explanation: Each letter shifted +2.
If BAT is coded as EDX, how is CAT coded?
Answer: FDW
Explanation: Each letter shifted +3.
If DOG is coded as FQI, how is CAT coded?
Answer: ECV
Explanation: Each letter shifted +2.
If APPLE is coded as BQQMF, how is MANGO coded?
Answer: NBOHP
Explanation: Each letter shifted +1.
If STAR is coded as TUBS, how is MOON coded?
Answer: NPPQ
Explanation: Each letter shifted +1.
If BOOK is coded as DQQL, how is PAGE coded?
Answer: RCIG
Explanation: Each letter shifted +2.
If CAT is coded as DBU, how is DOG coded?
Answer: EPH
Explanation: Each letter shifted +1.
If FISH is coded as GJTI, how is BIRD coded?
Answer: CJSE
Explanation: Each letter shifted +1.
If TREE is coded as USFF, how is LEAF coded?
Answer: MFBG
Explanation: Each letter shifted +1.
If CAT is coded as XZG, how is DOG coded?
Answer: ALD
Explanation: Each letter shifted -3.
If ROSE is coded as TQUG, how is LILY coded?
Answer: NKNA
Explanation: Each letter shifted +2.
If BOOK is coded as DQQL, how is PAGE coded?
Answer: RCIG
Explanation: Each letter shifted +2.
If SUM is coded as TVN, how is WIN coded?
Answer: XJO
Explanation: Each letter shifted +1.
If KING is coded as MJPI, how is QUEEN coded?
Answer: TXHHQ
Explanation: Each letter shifted +3.
Symbol Coding / Word-Substitution Coding (41–70)
If "Sky is blue" is coded as "@ # $", "Blue is deep" is coded as "$ # %", what is the code for "is"?
Answer: #
Explanation: "is" is common, # is common code.
If "Sun rises in east" is coded as "α β γ δ", "Moon rises in west" is coded as "ε β γ ζ", what is the code for "rises"?
Answer: β
Explanation: "rises" is common, β is common code.
"Apple is sweet" = "pi ka lo", "Mango is sweet" = "ka lo mi", "Apple is ripe" = "pi ka ni". What is the code for "sweet"?
Answer: lo
Explanation: "sweet" is common in first two, lo is common code.
"Red is beautiful" = "ka la ma", "Blue is beautiful" = "pa la ma", "Red is bright" = "ka la na". What is the code for "red"?
Answer: ka
Explanation: "red" is common in first and third, ka is common code.
"He is tall" = "mi ki si", "She is tall" = "li ki si", "He is short" = "mi ki ti". What is the code for "he"?
Answer: mi
Explanation: "he" is common in first and third, mi is common code.
"Good boy wins" = "pa ra sa", "Bad boy loses" = "ta ra va", "Good girl wins" = "pa la sa". What is the code for "wins"?
Answer: sa
Explanation: "wins" is common in first and third, sa is common code.
"Pen and paper" = "ka la ma", "Paper and ink" = "la ma na", "Pen and ink" = "ka la na". What is the code for "and"?
Answer: la
Explanation: "and" is common in all, la is common code.
"Book is heavy" = "ka la ma", "Book is light" = "ka la na", "Bag is heavy" = "pa la ma". What is the code for "heavy"?
Answer: ma
Explanation: "heavy" is common in first and third, ma is common code.
"Car is fast" = "ka la ma", "Bike is fast" = "pa la ma", "Car is slow" = "ka la na". What is the code for "car"?
Answer: ka
Explanation: "car" is common in first and third, ka is common code.
"Sun rises east" = "ka la ma", "Moon rises west" = "pa la na", "Sun sets east" = "ka ra ma". What is the code for "east"?
Answer: ma
Explanation: "east" is common in first and third, ma is common code.
"Dog barks loud" = "ka la ma", "Cat meows loud" = "pa ra ma", "Dog meows soft" = "ka ra na". What is the code for "dog"?
Answer: ka
Explanation: "dog" is common in first and third, ka is common code.
"Sky is clear" = "ka la ma", "Sky is blue" = "ka la na", "Water is clear" = "pa la ma". What is the code for "clear"?
Answer: ma
Explanation: "clear" is common in first and third, ma is common code.
"Pen is blue" = "ka la ma", "Pen is red" = "ka la na", "Book is blue" = "pa la ma". What is the code for "blue"?
Answer: ma
Explanation: "blue" is common in first and third, ma is common code.
"Apple is red" = "ka la ma", "Apple is green" = "ka la na", "Mango is red" = "pa la ma". What is the code for "apple"?
Answer: ka
Explanation: "apple" is common in first and second, ka is common code.
"He is honest" = "ka la ma", "She is honest" = "pa la ma", "He is clever" = "ka la na". What is the code for "he"?
Answer: ka
Explanation: "he" is common in first and third, ka is common code.
"Sun is bright" = "ka la ma", "Moon is bright" = "pa la ma", "Sun is hot" = "ka la na". What is the code for "sun"?
Answer: ka
Explanation: "sun" is common in first and third, ka is common code.
"Pen is black" = "ka la ma", "Pen is blue" = "ka la na", "Book is black" = "pa la ma". What is the code for "black"?
Answer: ma
Explanation: "black" is common in first and third, ma is common code.
"Book is thick" = "ka la ma", "Book is thin" = "ka la na", "Bag is thick" = "pa la ma". What is the code for "thick"?
Answer: ma
Explanation: "thick" is common in first and third, ma is common code.
"Sky is blue" = "ka la ma", "Sea is blue" = "pa la ma", "Sky is clear" = "ka la na". What is the code for "sky"?
Answer: ka
Explanation: "sky" is common in first and third, ka is common code.
"Pen is sharp" = "ka la ma", "Pen is blunt" = "ka la na", "Knife is sharp" = "pa la ma". What is the code for "sharp"?
Answer: ma
Explanation: "sharp" is common in first and third, ma is common code.
"Sun is hot" = "ka la ma", "Sun is cool" = "ka la na", "Moon is cool" = "pa la na". What is the code for "cool"?
Answer: na
Explanation: "cool" is common in second and third, na is common code.
"Flower is red" = "ka la ma", "Flower is white" = "ka la na", "Rose is red" = "pa la ma". What is the code for "flower"?
Answer: ka
Explanation: "flower" is common in first and second, ka is common code.
"Book is new" = "ka la ma", "Book is old" = "ka la na", "Bag is new" = "pa la ma". What is the code for "new"?
Answer: ma
Explanation: "new" is common in first and third, ma is common code.
"Pen is long" = "ka la ma", "Pen is short" = "ka la na", "Knife is long" = "pa la ma". What is the code for "long"?
Answer: ma
Explanation: "long" is common in first and third, ma is common code.
"Sun is bright" = "ka la ma", "Sun is round" = "ka la na", "Moon is round" = "pa la na". What is the code for "round"?
Answer: na
Explanation: "round" is common in second and third, na is common code.
"Pen is thin" = "ka la ma", "Pen is thick" = "ka la na", "Book is thin" = "pa la ma". What is the code for "thin"?
Answer: ma
Explanation: "thin" is common in first and third, ma is common code.
"Sky is clear" = "ka la ma", "Sky is cloudy" = "ka la na", "Sea is clear" = "pa la ma". What is the code for "clear"?
Answer: ma
Explanation: "clear" is common in first and third, ma is common code.
"Book is big" = "ka la ma", "Book is small" = "ka la na", "Bag is big" = "pa la ma". What is the code for "big"?
Answer: ma
Explanation: "big" is common in first and third, ma is common code.
"Pen is new" = "ka la ma", "Pen is old" = "ka la na", "Book is new" = "pa la ma". What is the code for "new"?
Answer: ma
Explanation: "new" is common in first and third, ma is common code.
"Sun is bright" = "ka la ma", "Sun is hot" = "ka la na", "Moon is hot" = "pa la na". What is the code for "hot"?
Answer: na
Explanation: "hot" is common in second and third, na is common code.
Number Coding (71–100)
If CAT is coded as 3 1 20, how is DOG coded?
Answer: 4 15 7
Explanation: Alphabet positions.
If APPLE is coded as 1 16 16 12 5, how is MANGO coded?
Answer: 13 1 14 7 15
Explanation: Alphabet positions.
If TREE is coded as 20 18 5 5, how is LEAF coded?
Answer: 12 5 1 6
Explanation: Alphabet positions.
If ROSE is coded as 18 15 19 5, how is LILY coded?
Answer: 12 9 12 25
Explanation: Alphabet positions.
If SUM is coded as 19 21 13, how is WIN coded?
Answer: 23 9 14
Explanation: Alphabet positions.
If STAR is coded as 19 20 1 18, how is MOON coded?
Answer: 13 15 15 14
Explanation: Alphabet positions.
If CAT is coded as 24 1 20, how is DOG coded?
Answer: 23 15 7
Explanation: C→24 (27-3), A→1, T→20; D→23 (27-4), O→15, G→7.
If PEN is coded as 16 5 14, how is INK coded?
Answer: 9 14 11
Explanation: Alphabet positions.
If LEMON is coded as 12 5 13 15 14, how is ORANGE coded?
Answer: 15 18 1 14 7 5
Explanation: Alphabet positions.
If BOOK is coded as 2 15 15 11, how is PAGE coded?
Answer: 16 1 7 5
Explanation: Alphabet positions.
If CAT is coded as 3 1 20, how is DOG coded?
Answer: 4 15 7
Explanation: Alphabet positions.
If FISH is coded as 6 9 19 8, how is BIRD coded?
Answer: 2 9 18 4
Explanation: Alphabet positions.
If TREE is coded as 20 18 5 5, how is LEAF coded?
Answer: 12 5 1 6
Explanation: Alphabet positions.
If ROSE is coded as 18 15 19 5, how is LILY coded?
Answer: 12 9 12 25
Explanation: Alphabet positions.
If SUM is coded as 19 21 13, how is WIN coded?
Answer: 23 9 14
Explanation: Alphabet positions.
If STAR is coded as 19 20 1 18, how is MOON coded?
Answer: 13 15 15 14
Explanation: Alphabet positions.
If CAT is coded as 3 1 20, how is DOG coded?
Answer: 4 15 7
Explanation: Alphabet positions.
If PEN is coded as 16 5 14, how is INK coded?
Answer: 9 14 11
Explanation: Alphabet positions.
If LEMON is coded as 12 5 13 15 14, how is ORANGE coded?
Answer: 15 18 1 14 7 5
Explanation: Alphabet positions.
If BOOK is coded as 2 15 15 11, how is PAGE coded?
Answer: 16 1 7 5
Explanation: Alphabet positions.
If CAT is coded as 24 1 20, how is DOG coded?
Answer: 23 15 7
Explanation: C→24 (27-3), A→1, T→20; D→23 (27-4), O→15, G→7.
If FISH is coded as 6 9 19 8, how is BIRD coded?
Answer: 2 9 18 4
Explanation: Alphabet positions.
If TREE is coded as 20 18 5 5, how is LEAF coded?
Answer: 12 5 1 6
Explanation: Alphabet positions.
If ROSE is coded as 18 15 19 5, how is LILY coded?
Answer: 12 9 12 25
Explanation: Alphabet positions.
If SUM is coded as 19 21 13, how is WIN coded?
Answer: 23 9 14
Explanation: Alphabet positions.
If STAR is coded as 19 20 1 18, how is MOON coded?
Answer: 13 15 15 14
Explanation: Alphabet positions.
If CAT is coded as 3 1 20, how is DOG coded?
Answer: 4 15 7
Explanation: Alphabet positions.
If PEN is coded as 16 5 14, how is INK coded?
Answer: 9 14 11
Explanation: Alphabet positions.
If LEMON is coded as 12 5 13 15 14, how is ORANGE coded?
Answer: 15 18 1 14 7 5
Explanation: Alphabet positions.
If BOOK is coded as 2 15 15 11, how is PAGE coded?
Answer: 16 1 7 5
Explanation: Alphabet positions.
These questions cover all major patterns of letter shifting, symbol coding, and number coding. For more questions and detailed explanations, you can practice on resources like Hitbullseye, Testbook, BYJU'S, and Smartkeeda123456.
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