CODING AND DECODING
What is Coding & Decoding?
Coding and decoding are processes within the domain of logical reasoning and puzzles, often found in competitive exams and aptitude tests. These tasks involve transforming a given message or information using specific rules or patterns.
Coding:
- Coding is the process of converting a message or information into a different form or language based on a given rule or pattern.
- It involves substituting letters, numbers, or symbols in a particular sequence or manner as per the given instructions.
- The goal is to encode the information according to the specified rule.
Decoding:
- Decoding is the reverse process of coding. It involves interpreting or translating an encoded message back to its original form using the same rule or pattern.
- The task is to understand the given rule and apply it in reverse to decipher the encoded information.
Example:
For instance, a coding rule might instruct to replace every letter with the one following it in the alphabet. If 'A' becomes 'B', 'B' becomes 'C', and so on.
- Coding: "HELLO" might become "IFMMP" following the rule (H → I, E → F, L → M, O → P).
- Decoding: To decipher "IFMMP" back to "HELLO," simply reverse the process by going one letter back in the alphabet for each character
Position Value and Alphabet Letters (Forward & Backward Direction)
| Letter | Positional Value | Decimal Value (ASCII) |
|---|---|---|
| A | 1 | 65 |
| B | 2 | 66 |
| C | 3 | 67 |
| D | 4 | 68 |
| E | 5 | 69 |
| F | 6 | 70 |
| G | 7 | 71 |
| H | 8 | 72 |
| I | 9 | 73 |
| J | 10 | 74 |
| K | 11 | 75 |
| L | 12 | 76 |
| M | 13 | 77 |
| N | 14 | 78 |
| O | 15 | 79 |
| P | 16 | 80 |
| Q | 17 | 81 |
| R | 18 | 82 |
| S | 19 | 83 |
| T | 20 | 84 |
| U | 21 | 85 |
| V | 22 | 86 |
| W | 23 | 87 |
| X | 24 | 88 |
| Y | 25 | 89 |
| Z | 26 | 90 |
| Letter | Forward Positional Value | Backward Positional Value |
|---|---|---|
| A | 1 | 26 |
| B | 2 | 25 |
| C | 3 | 24 |
| D | 4 | 23 |
| E | 5 | 22 |
| F | 6 | 21 |
| G | 7 | 20 |
| H | 8 | 19 |
| I | 9 | 18 |
| J | 10 | 17 |
| K | 11 | 16 |
| L | 12 | 15 |
| M | 13 | 14 |
| N | 14 | 13 |
| O | 15 | 12 |
| P | 16 | 11 |
| Q | 17 | 10 |
| R | 18 | 9 |
| S | 19 | 8 |
| T | 20 | 7 |
| U | 21 | 6 |
| V | 22 | 5 |
| W | 23 | 4 |
| X | 24 | 3 |
| Y | 25 | 2 |
| Z | 26 | 1 |
Table indicates each alphabet's position in the English alphabet, starting with 'A' having a positional value of 1 and 'Z' with a positional value of 26. Understanding these positional values is essential in various tasks involving coding, decoding, and other logical reasoning exercise
1.Letter Shifting/Alphabet Coding:
- Type: Substituting each letter of a word or phrase with a letter that appears a certain number of positions later or earlier in the alphabet.
- Example: "CAT" becomes "FED" by shifting each letter three positions forward (C → F, A → E, T → D).
2. Number Coding:
- Type: Replacing letters in a word with numerical values based on their positions in the alphabet.
- Example: "HELLO" might be coded as "85121215" (H → 8, E → 5, L → 12, O → 15).
3. Symbol/Substitution Coding:
- Type: Substituting letters, numbers, or symbols based on predefined rules or patterns.
- Example: A circle represents a vowel, a square represents a consonant, or specific symbols denote particular letters.
4. Mixed Coding:
- Type: Combining different coding rules in a single question to encode or decode a message.
- Example: Using both letter shifting and number substitution rules within the same code.
5. Mathematical Operations Coding:
- Type: Applying mathematical operations (addition, subtraction, multiplication, division) to each letter/number in a given word or phrase.
- Example: "APPLE" might become "CRRNG" by adding two to each letter (A + 2 = C, P + 2 = R, etc.).
6. Conditional Coding:
- Type: Coding/decoding based on specific conditions, like conditional statements, positional arrangements, or logical sequences.
- Example: Encoding or decoding based on the positions of vowels, consonants, or alternate letters.
7. Passage Coding/Decoding:
- Type: Coding or decoding a passage where rules for substitution, rearrangement, or transformation are provided.
- Example: Replacing certain words or letters according to a given rule or pattern within a paragraph or sentence.
8. Analogy-Based Coding:
- Type: Establishing relationships between words and using those relationships to encode or decode.
- Example: If "Sun" is coded as "21", "Moon" might be coded as "253".
9. Sentence Coding:
- Type: Coding entire sentences based on specific rules applied to each word or to the sentence as a whole.
- Example: Rearranging words or substituting them with numbers/symbols according to predefined rules.
How to Solve Coding Decoding Questions in Reasoning– Tips and Tricks
1. Understand the Coding Rule:
- Analyze the Pattern: Identify the rule or pattern used for encoding or decoding the message.
- Look for Regularity: Observe if there's a consistent shift, mathematical operation, or substitution rule applied.
2. Work with Keywords:
- Identify Keywords: Look for key words or letters that could indicate the coding rule.
- Focus on Changes: Pay attention to the differences between the original and coded message.
3. Utilize Positional Values:
- Know Alphabet Positions: Understand the positions of letters in the alphabet to decipher letter-shifting codes.
- Number Correspondence: Relate numbers to their respective alphabet positions to solve numerical coding.
4. Analyze Word Structure:
- Split Words: Break down words into individual letters to decipher the coding pattern.
- Check for Patterns: Observe how vowels, consonants, or specific letter combinations are treated.
5. Use Reverse Coding:
- Reverse Engineer: Try reversing the applied rule to decode the message, especially if the encoding method is clear.
6. Test with Options:
- Trial and Error: If multiple-choice options are available, test potential solutions to identify the correct coding rule.
- Elimination Strategy: Eliminate options that do not adhere to the identified pattern.
7. Practice Different Patterns:
- Variety in Practice: Solve diverse types of coding and decoding problems to familiarize yourself with various patterns.
- Mock Tests: Take practice tests and solve sample questions to improve speed and accuracy.
8. Avoid Assumptions:
- Stick to the Given Rule: Do not assume patterns that are not explicitly stated in the question.
- Verify Your Solution: Double-check if the decoded message aligns with the given rule.
9. Mental Calculation:
- Quick Mental Math: Improve mental math skills to perform faster calculations during numerical or mathematical coding
Sample Coding Decoding Questions
| Question | Code Type | Explanation |
|---|---|---|
| If CAT is coded as DOG, how is DOG coded? | Substitution | Each letter is shifted two positions forward in the alphabet (C>E, A>C, T>V). So, DOG translates to FPH. |
| In a certain code, BIRD is 2134, TREE is 3549 and SKY is 198. What is CLOUD? | Number Substitution | Each letter corresponds to a unique number. B=2, I=1, R=3, D=4, T=5, etc. CLOUD would be 34159. |
| The letters of a word are reversed and then each letter is moved one position backwards in the alphabet. If the coded word is YMJW, what is the original word? | Reverse Alphabet Shift | Decode by reversing YMJW (WJMY) and then shifting each letter back one (VIMX). V=W, I=J, M=N, X=Y. The original word is VINY. |
| In this code, each vowel is replaced by the next vowel in the alphabet (a->e, e->i, i->o, o->u, u->a). Consonants remain unchanged. What is the code for RAINBOW? | Vowel Shift | Code: EAINBOW (R, B, and W stay the same). |
| If the first and last letters of each word are swapped, what is the code for SUNSHINE? | First-Last Swap | Code: NISNUHS (S and E are swapped in SUNSHINE). |
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Practice Questions on Coding and Decoding
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