Coding-Decoding Reasoning Questions With Answers and Tricks

TL;DR: Coding-decoding questions give you a word, number, or sentence written in a secret code and ask you to find the rule behind it. Most codes rely on a small set of patterns: shifting letters, reversing them, swapping them for their opposite letters, or turning them into numbers. Memorizing letter positions and checking patterns in a fixed order will solve most questions in under a minute.

Coding decoding questions show up in almost every aptitude test in India, from bank and SSC exams to campus placement rounds at IT companies. They look intimidating at first because the codes seem random. They aren't. Nearly every question comes from the same handful of rules, and once you spot them, this becomes one of the fastest sections to score in.

This guide explains what coding-decoding in reasoning is, walks through each question type with an example, and shares the tricks that cut solving time. It ends with 30 coding-decoding reasoning questions, sorted from easy to hard, each with an answer and explanation.

What Is Coding-Decoding in Reasoning?

Coding is the process of converting a word, number, or sentence into a different form using a fixed rule. Decoding works backward: you find that rule and apply it to reveal or create another code.

The basic rule of coding and decoding is consistency. Whatever rule turns the first word into its code will turn the second word into its code too. Your job is to find that rule from the example given, then apply it.

Here's a simple example. If CAT is coded as DBU, each letter has moved one step forward in the alphabet (C→D, A→B, T→U). Using the same rule, DOG becomes EPH.

Boost Your Coding Skills. Nail Your Next InterviewAI-Powered Full Stack Developer ProgramExplore Program

Types of Coding-Decoding Questions

Most coding-decoding questions fall into one of the types below. Knowing them helps you guess the rule faster.

1. Letter Shift Coding

Each letter moves forward or backward by a fixed number of places. The shift can be the same for every letter, alternate between two values, or increase with each position.

Example: If MONKEY is coded as KMLICW, how is ORANGE coded? Each letter moves back 2 places. Apply the same to ORANGE: O→M, R→P, A→Y, N→L, G→E, E→C. Answer: MPYLEC. Note how A wraps around to Y. Wrap-arounds are where most mistakes happen.

2. Reverse and Opposite Letter Coding

In reverse coding, you write the word backward (STAR becomes RATS). In opposite-letter coding, each letter is replaced by its mirror in the alphabet: A with Z, B with Y, C with X, and so on.

Example: Using opposite letters, CAT is coded as XZG (C↔X, A↔Z, T↔G).

3. Letter to Number Coding

A number replaces each letter, usually its position in the alphabet (A = 1, B = 2 ... Z = 26). Variations use reverse positions (A = 26), squares of positions, or the sum of all positions in the word.

Example: If A = 1, B = 2, and so on, DOG is coded as 4157 (D = 4, O = 15, G = 7).

4. Number to Letter Coding

The reverse of the previous type: numbers are given, and you convert them to letters.

Example: If 1 = A, 2 = B, and so on, then 3-1-18 decodes to CAR.

5. Substitution Coding

One word is given the name of another, and you answer using the substituted name.

Example: If white is called red, red is called blue, blue is called green, green is called yellow, and yellow is called black, what is the color of blood? Blood is red, and red is called blue. Answer: Blue.

6. Symbol Coding

Letters or digits are replaced by symbols such as @, #, $, or %. Map each character to its symbol and read the code directly.

Example: If R = £, A = &, and T = #, then TAR is coded as #&£.

7. Mixed Coding (Chinese Coding)

Several sentences are given in a code language, and you find the code for one word by comparing statements. The word common to two sentences takes the code common to both.

Example: "Ha ka bow" means "How are you" and "ka te ma" means "where are they." What is the code for "are"? The only common word is "are," and the only common code is "ka." Answer: ka.

8. Conditional Coding

Letters are given codes in a table, but special conditions change the code when certain patterns appear, such as a word starting with a vowel. You apply the table, then check each condition in order. These are common in bank exams and are covered in the hard practice questions below.

9. New Pattern Sentence Coding

A newer variation in bank exams, where whole sentences are coded as groups of letters or syllables. Solve it the same way as mixed coding, but with more statements and words, so track eliminations carefully.

Tricks and Shortcuts for Coding-Decoding

Speed in code decode reasoning questions comes from not having to count through the alphabet. These shortcuts help the most.

Memorize Letter Positions

Use the EJOTY Anchor

EJOTY marks every fifth letter: E = 5, J = 10, O = 15, T = 20, Y = 25. To find R, start at O (15) and count three forward to get 18. You never have to count from A.

Know the Opposite Letter Pairs

A quick check: every opposite pair adds up to 27. The opposite of any letter is 27 minus its position, so the opposite of H (8) is the letter at 19, which is S.

Check Patterns in a Fixed Order

When a code doesn't click right away, test rules in this order instead of guessing:

1. Is the code the same length as the word? If not, look for number or symbol coding.
2. Compare the word's first letter with the code's first letter. Is it a fixed shift?
3. If the shift changes, is it alternating (+1, −1) or increasing (+1, +2, +3)?
4. Is the word reversed, or split in halves with each half reversed?
5. Do their opposites replace the letters?
6. For numbers, try positions, reverse positions, squares, and sums.

Get the Coding Skills You Need to SucceedAI-Powered Full Stack Developer ProgramExplore Program

How to Solve Coding-Decoding Questions Quickly

1. Write the word and its code one above the other, letter under letter, so the pattern is visible.
2. Convert letters to positions for the first two or three pairs and note the difference.
3. Confirm the rule on every letter, not just the first one. Many options are designed to trap you after two correct letters.
4. Apply the rule to the new word and write the code out in full.
5. Match against the options, and use elimination if two options differ in only one letter.

For mixed or sentence coding, skip the letter work. Compare statements two at a time, circle the common word and common code, and cross off what you've already identified.

Coding Decoding Questions With Answers

The 30 coding-decoding reasoning questions below are sorted by difficulty. Try each one before reading the explanation.

Easy Level (Questions 1 to 10)

Q1. If BOOK is coded as CPPL, how is PAGE coded? Answer: QBHF. Each letter moves one place forward: P→Q, A→B, G→H, E→F.

Q2. If ROAD is coded as URDG, how is SWAN coded? Answer: VZDQ. Each letter moves three places forward: S→V, W→Z, A→D, N→Q.

Q3. If PENCIL is coded as LICNEP, how is ERASER coded? Answer: RESARE. The word is simply written backward.

Q4. If BAD is coded as 214, how is FACE coded? Answer: 6135. Each letter is replaced by its position: F = 6, A = 1, C = 3, E = 5.

Q5. If 8-5-12-16 stands for HELP, what does 19-1-6-5 stand for? Answer: SAFE. Each number is a letter position: 19 = S, 1 = A, 6 = F, 5 = E.

Q6. If CAT = 24, what is the value of DOG? Answer: 26. CAT is the sum of its letter positions (3 + 1 + 20 = 24). DOG = 4 + 15 + 7 = 26.

Q7. If sky is called sea, sea is called water, water is called air, air is called cloud, and cloud is called rain, where do fish live? Answer: Water. Fish live in the sea, and in this code, sea is called water.

Q8. If M = $, A = #, T = @, and E = %, how is TEAM coded? Answer: @%#$. Replace each letter with its symbol in order: T = @, E = %, A = #, M = $.

Q9. If HOUSE is coded as 35842 and LEMON as 12659, how is HELEN coded? Answer: 32129. From the two codes, H = 3, E = 2, L = 1, N = 9. Both codes agree on E and O, which confirms a letter-for-digit mapping.

Q10. In a code where each letter is shifted two places forward, what word is coded as JQRG? Answer: HOPE. To decode, shift each letter two places back: J→H, Q→O, R→P, G→E.

Also Read: Logical Reasoning Interview Questions and Answers

Medium Level (Questions 11 to 20)

Q11. If GOLD is coded as TLOW, how is SILVER coded? Answer: HROEVI. Each letter is replaced by its opposite: S↔H, I↔R, L↔O, V↔E, E↔V, R↔I.

Q12. If TABLE is coded as UZCKF, how is CHAIR coded? Answer: DGBHS. The shift alternates between +1 and −1: C+1 = D, H−1 = G, A+1 = B, I−1 = H, R+1 = S.

Q13. If FACE is coded as GCFI, how is BOLD coded? Answer: CQOH. The shift increases by one for each letter (+1, +2, +3, +4): B→C, O→Q, L→O, D→H.

Q14. If MOTHER is coded as SFIUPN, how is FATHER coded? Answer: SFIUBG. The word is reversed (REHTOM), then each letter moves one place forward (SFIUPN). FATHER reversed is REHTAF, which becomes SFIUBG.

Q15. If PLANET is coded as ALPTEN, how is FRIEND coded? Answer: IRFDNE. The word is split into two halves, and each half is reversed: PLA→ALP, NET→TEN. So FRI→IRF and END→DNE.

Q16. If ACE is coded as 1925, how is BAD coded? Answer: 4116. Each letter is replaced by the square of its position: A = 1, C = 9, E = 25. So B = 4, A = 1, D = 16.

Q17. If A = 26, B = 25, and so on until Z = 1, how is JOB coded? Answer: 171225. Use reverse positions: J = 17, O = 12, B = 25.

Q18. If PAINT is coded as 74128 and EXCEL as 93596, how is ACCEPT coded? Answer: 455978. From the two codes, A = 4, C = 5, E = 9, P = 7, T = 8. Both E's in EXCEL are coded as 9, which confirms the mapping.

Q19. In a code language, "pic tu mo" means "sky is blue," "tu la na" means "blue and green," and "na ri pic" means "green is grass." What is the code for "sky"? Answer: mo. "Blue" appears in the first two sentences, and "tu" is the common code, so blue = tu. "Is" appears in the first and third, so is = pic. That leaves sky = mo.

Q20. In a code, "246" means "good sweet fruit," "635" means "sweet red apple," and "478" means "fruit is fresh." Which digit stands for "good"? Answer: 2. Sweet is common to the first two statements, so sweet = 6. Fruit is common to the first and third, so fruit = 4. The remaining digit in "246" is 2, so good = 2.

Hard Level (Questions 21 to 30)

Questions 21 to 23 use the table and conditions below.

Conditions:

• (i) If the first letter is a vowel and the last letter is a consonant, their codes are interchanged.
• (ii) If both the first and last letters are consonants, both are coded as *.

Q21. What is the code for EMKTP? Answer: 85369. The direct code is 9 5 3 6 8. The word starts with a vowel (E) and ends with a consonant (P), so condition (i) applies and the first and last codes are swapped.

Q22. What is the code for BRAKM? Answer: *243*. B and M are both consonants, so condition (ii) applies. The middle letters keep their codes: R = 2, A = 4, K = 3.

Q23. What is the code for DEKRU? Answer: 1932%. D is a consonant, and U is a vowel, so neither condition applies. Use the table directly.

Q24. In a code language, "ka lo mi" means "sun rise early," "mi pa to" means "early bird wins," and "pa ka re" means "bird sun song." What is the code for "wins"? Answer: to. Early is common to the first two statements, so early = mi. Bird is common to the second and third, so bird = pa. In "mi pa to," the only code left is "to," so wins = to.

Q25. If COMPUTER is coded as RFUVQNPC, how is MEDICINE coded? Answer: EOJDJEFM. The first and last letters swap places. The middle letters (OMPUTE) move one place forward (PNQVUF) and are then written in reverse (FUVQNP). For MEDICINE: M and E swap; EDICIN becomes FEJDJO, which reversed is OJDJEF. Result: E + OJDJEF + M.

Q26. If DELHI is coded as 73541 and CALCUTTA as 82589662, how is CALICUT coded? Answer: 8251896. Each letter has a fixed digit: C = 8, A = 2, L = 5, I = 1, U = 9, T = 6. L is coded as 5 in both words, which confirms the mapping.

Q27. In a code, each letter is replaced by its opposite letter, and the result is then written backward. How is BRAIN coded? Answer: MRZIY. The opposites of B, R, A, I, N are Y, I, Z, R, M, giving YIZRM. Written backward, that is MRZIY.

Q28. If DOG = 78 and CAT = 72, what is the value of COW? Answer: 123. The rule is to sum the letter positions and multiply by the number of letters. DOG: (4 + 15 + 7) × 3 = 78. CAT: (3 + 1 + 20) × 3 = 72. COW: (3 + 15 + 23) × 3 = 123.

Q29. If GRAPE = 47, what is the value of APPLE? Answer: 50. GRAPE is the sum of its positions (7 + 18 + 1 + 16 + 5 = 47). APPLE = 1 + 16 + 16 + 12 + 5 = 50. Watch for repeated letters; each one is counted.

Q30. In a code, the first letter moves one place forward, the second two places, the third three places, and so on. What word is coded as IGOPT? Answer: HELLO. Decode by moving each letter back by its position: I−1 = H, G−2 = E, O−3 = L, P−4 = L, T−5 = O.

Exams and Placement Tests That Include Coding-Decoding

Question difficulty varies widely. SSC and placement tests lean toward letter shift and letter-to-number questions. Bank mains exams favor conditional coding and new pattern sentence coding.

Learn 45+ in-demand full-stack development skills and tools, including Frontend Development, Backend Development, Version Control and Collaboration, Database Management, and AI-Assisted Development, with our Full Stack Developer Course.

Common Mistakes to Avoid

• Checking only the first two letters. Question setters often build distractors that match the first letters and break later.
• Forgetting to wrap around. One step past Z is A, and one step before A is Z.
• Mixing up positions and reverse positions. Decide which one the question uses before calculating.
• Applying conditional rules in the wrong order. Check each condition exactly as listed, and only apply the one that matches.
• Assuming a word is in more sentences than it is. In mixed coding, underline each word's appearances before comparing codes.

Key Takeaways

• Coding-decoding questions test whether you can find a consistent rule and apply it to a new word, number, or sentence.
• Most questions use letter shifts, reversals, opposite letters, number positions, substitution, symbols, or statement comparison.
• Memorizing letter positions, the EJOTY anchors, and opposite pairs removes most of the counting.
• Always verify the rule on every letter before choosing an answer.
• Practicing across difficulty levels prepares you for both placement tests and bank mains exams.

Conclusion

Coding-decoding rewards pattern recognition more than raw calculation. Learn the question types, keep the position tables at your fingertips, and check rules in a fixed order, and most questions will take under a minute. Work through the 30 practice questions above until the patterns feel automatic.

Aptitude rounds are often the first filter in tech hiring. If you're preparing for placements and want to build the technical skills that follow, Simplilearn's Full Stack Developer Course pairs hands-on projects with interview preparation. You can also explore Simplilearn’s Software Development courses to build broader programming and software engineering skills for real-world development. 

FAQs

1. How many coding-decoding questions have been asked in the exam?

Depending on the exams, some have a handful of coding-decoding questions within the reasoning aptitude section. Bank mains level exams often have a complete set of coding decoding based on conditional or sentence coding. Check the syllabus and previous papers on the exam you want to attempt.

2. How long should I take for each question?

Letter and number-based questions should not take more than 30-45 seconds. In a set of conditional or sentence coding, try to take 60 seconds for each question. If you can’t decipher the pattern in a minute, move on to the next and return to it later.

3. What’s the difference between coding-decoding and cryptography?

They have nothing to do with each other. Coding-decoding is a simple logic-based question that asks you to identify the pattern. Meanwhile, cryptography is a field in computer science that uses mathematical algorithms to encrypt data.

4. What to do if none of the patterns are working?

Go back to the checklist and try the uncommon patterns like squares of the position of letters, the sum multiplied by the word length, split and reverse, or reverse the alphabetical position of letters. Don’t forget to check if the question has reversed positions or alphabetical positions instead.

5. Can coding-decoding questions have more than one possible answer?

A well-set question has only one rule that fits all the letters given. If two rules seem to work, test both against the answer options. Usually only one appears in the choices.

6. Do I need to memorize the full alphabet position table?

It helps, but the EJOTY anchors get you most of the way. With E, J, O, T, and Y memorized, any letter's position is at most two steps away. The only exceptions are A and B, which are easy to remember because they open the alphabet.