Coding decoding questions

Reasoning Updated 11 Oct 2026

These coding decoding questions help you practise one of the most common reasoning topics in SSC, bank, railway and placement tests. The 30 questions on this page cover letter shifting, opposite letters, reversed words, letter to number codes, mixed shift patterns and sentence coding, and every answer has a worked explanation.

The sets move from easy to hard, so beginners can start at the top and exam aspirants can jump to the medium and hard coding decoding reasoning questions.

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Letter shifting coding decoding questions (easy)

Q1. If CAT is coded as DBU, how is DOG coded in the same language?
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Answer: A. EPH
Each letter of CAT is moved 1 place forward (C +1 = D). Applying the same rule, DOG becomes EPH.
Q2. If BOOK is coded as DQQM, how is PAGE coded in the same language?
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Answer: C. RCIG
Each letter of BOOK is moved 2 places forward (B +2 = D). Applying the same rule, PAGE becomes RCIG.
Q3. If LAMP is coded as KZLO, how is DESK coded in the same language?
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Answer: B. CDRJ
Each letter of LAMP is moved 1 place backward (L -1 = K). Applying the same rule, DESK becomes CDRJ.
Q4. If MILK is coded as PLON, how is JUICE coded in the same language?
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Answer: D. MXLFH
Each letter of MILK is moved 3 places forward (M +3 = P). Applying the same rule, JUICE becomes MXLFH.
Q5. If RIVER is coded as PGTCP, how is OCEAN coded in the same language?
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Answer: D. MACYL
Each letter of RIVER is moved 2 places backward (R -2 = P). Applying the same rule, OCEAN becomes MACYL.
Q6. If PLANT is coded as TPERX, how is GREEN coded in the same language?
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Answer: B. KVIIR
Each letter of PLANT is moved 4 places forward (P +4 = T). Applying the same rule, GREEN becomes KVIIR.
Q7. In a certain code, each letter is written as the next letter of the alphabet. Which word is coded as USBJO?
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Answer: A. TRAIN
Decode by moving each letter one place back: U S B J O gives T R A I N.

Reverse and opposite letter coding

Q8. If each letter is replaced by its opposite letter in the alphabet (A to Z, B to Y and so on), how is GOLD written?
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Answer: C. TLOW
Opposite letters add up to 27 in position: G (7) to T (20), O (15) to L (12), L (12) to O (15), D (4) to W (23). So GOLD is coded as TLOW.
Q9. If each letter is replaced by its opposite letter in the alphabet (A to Z, B to Y and so on), how is FISH written?
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Answer: A. URHS
Opposite letters add up to 27 in position: F (6) to U (21), I (9) to R (18), S (19) to H (8), H (8) to S (19). So FISH is coded as URHS.
Q10. If each letter is replaced by its opposite letter in the alphabet (A to Z, B to Y and so on), how is HORSE written?
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Answer: C. SLIHV
Opposite letters add up to 27 in position: H (8) to S (19), O (15) to L (12), R (18) to I (9), S (19) to H (8), E (5) to V (22). So HORSE is coded as SLIHV.
Q11. If FRAME is coded as EMARF, how is STONE coded?
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Answer: B. ENOTS
The letters of FRAME are simply written in reverse order. Reversing STONE gives ENOTS.
Q12. If MANGO is coded as PHOBN, how is PEARL coded?
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Answer: D. MSBFQ
The word is reversed (MANGO to OGNAM) and then each letter is moved one place forward to give PHOBN. PEARL reversed is LRAEP, and +1 gives MSBFQ.

Letter to number coding questions

Q13. If ACE is coded as 9, how is BAD coded? (Code = sum of the letter positions)
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Answer: D. 7
ACE: 1 + 3 + 5 = 9. BAD: 2 + 1 + 4 = 7.
Q14. If DOG is coded as 26, how is CAT coded? (Code = sum of the letter positions)
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Answer: B. 24
DOG: 4 + 15 + 7 = 26. CAT: 3 + 1 + 20 = 24.
Q15. If HIDE is written as 8945, how is FACE written in that code?
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Answer: A. 6135
Each letter is replaced by its position number: H = 8, I = 9, D = 4, E = 5. So F = 6, A = 1, C = 3, E = 5 gives 6135.
Q16. In a code, BIG = 36. If the code is twice the sum of the letter positions, what is the code for TOP?
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Answer: C. 102
BIG: (2 + 9 + 7) x 2 = 36. TOP: (20 + 15 + 16) x 2 = 102.
Q17. If CAB is coded as 242625 using the reverse position of each letter (Z = 1, Y = 2 ... A = 26), what is the code for BED?
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Answer: A. 252223
Reverse position = 27 minus the normal position. B = 25, E = 22, D = 23, so BED = 252223.
Q18. If SUN is coded as 162, what is the code for MOON? (Code = sum of letter positions x number of letters)
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Answer: C. 228
SUN: (19 + 21 + 14) x 3 = 162. MOON: (13 + 15 + 15 + 14) x 4 = 57 x 4 = 228.

Mixed pattern coding (medium)

Q19. If WATER is coded as XCWIW, how is FLASH coded?
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Answer: B. GNDWM
The letters of WATER move by +1, +2, +3, +4 and +5 places in order. Applying the same shifts to FLASH gives GNDWM.
Q20. If CLOUD is coded as DKPTE, how is BRAIN coded?
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Answer: D. CQBHO
The letters of CLOUD move by +1, -1, +1, -1 and +1 places in order. Applying the same shifts to BRAIN gives CQBHO.
Q21. If SMART is coded as UKCPV, how is QUICK coded?
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Answer: D. SSKAM
The letters of SMART move by +2, -2, +2, -2 and +2 places in order. Applying the same shifts to QUICK gives SSKAM.
Q22. If NORTH is coded as SSUVI, how is DELTA coded?
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Answer: B. IIOVB
The letters of NORTH move by +5, +4, +3, +2 and +1 places in order. Applying the same shifts to DELTA gives IIOVB.
Q23. If PENCIL is coded as NEPLIC, how is SCHOOL coded?
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Answer: A. HCSLOO
The word is split into two halves of three letters and each half is reversed: PEN to NEP and CIL to LIC. So SCH becomes HCS and OOL becomes LOO.
Q24. If DEAR is coded as 56219, how is FAME coded?
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Answer: C. 72146
Each letter is written as its position plus one: D(4) = 5, E(5) = 6, A(1) = 2, R(18) = 19. So F = 7, A = 2, M = 14, E = 6 gives 72146.

Word and sentence coding (hard)

Q25. In a code language, 'sky is blue' is written as 'ta na pa' and 'blue is colour' is written as 'na pa ko'. What is the code for 'sky'?
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Answer: A. ta
'is' and 'blue' appear in both sentences, so they share the codes 'na' and 'pa'. The remaining word 'sky' must be 'ta'.
Q26. In a code language, 'good morning friend' is 'li mo ka', 'good night friend' is 'ka ro mo' and 'night is dark' is 'ro su ve'. What is the code for 'morning'?
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Answer: C. li
'good friend' is common to the first two sentences, so it is 'mo ka'. 'night' is common to the last two, so it is 'ro'. In the first sentence the only code left for 'morning' is 'li'.
Q27. If 'pen paper ink' is coded as '5 7 3' and 'ink book desk' is coded as '3 8 1', and 'paper book bag' is '7 8 2', what is the code for 'pen'?
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Answer: B. 5
'ink' is common to the first two sentences, so ink = 3. 'paper' is common to the first and third, so paper = 7. The only code left in the first sentence is 5, for 'pen'.
Q28. In a code language, 'red' is called 'green', 'green' is called 'yellow', 'yellow' is called 'white' and 'white' is called 'blue'. What is the colour of a parrot in that language?
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Answer: D. yellow
A parrot is green, and in this code 'green' is called 'yellow'. So the answer is yellow.
Q29. If 'sky' is called 'sea', 'sea' is called 'water', 'water' is called 'air' and 'air' is called 'cloud', what do we drink in that language?
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Answer: D. air
We drink water, and in this code 'water' is called 'air'.
Q30. In a code, 'come here soon' is 'xa ri po', 'soon go away' is 'po lu de' and 'come and go' is 'ri lu sa'. What is the code for 'here'?
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Answer: B. xa
'soon' is common to the first two sentences, so soon = po. 'come' is common to the first and third, so come = ri. The code left in the first sentence, xa, stands for 'here'.

How to prepare

To solve a coding question, first write the original word and its code one above the other and compare letter by letter. Find the shift for each letter using positions (A = 1 to Z = 26) and check whether it is constant, alternating, increasing or a reversal. Remember the opposite pairs: a letter and its opposite always add up to 27 (A and Z, M and N).

For sentence coding, look for words common to two sentences; their shared codes must match. Cross out every code you have fixed and the remaining code gives the answer. Learning the position of each letter by heart, with markers such as E = 5, J = 10, O = 15, T = 20, saves a lot of time in the exam.

Study tips

Memorise letter positions with the EJOTY trick (E 5, J 10, O 15, T 20, Y 25).
Always test the rule you found on every letter of the example, not just the first one.
In sentence coding, start with the word that appears in the most sentences.

Questions people ask

What are coding decoding questions in reasoning?

Coding decoding questions give a word, number or sentence written in a secret code and ask you to find the rule. You then use the same rule to code or decode another word. They appear in almost every competitive exam reasoning section.

How do I solve coding and decoding questions quickly?

Write the letter positions under the given word and its code and find the difference for each letter. Most patterns are a fixed shift, an alternating shift, a reversal or opposite letters, so check those first.

What is the opposite letter rule in coding decoding?

Opposite letters are pairs like A and Z or B and Y whose positions add up to 27. If a word is coded with opposite letters, subtract each position from 27 to get the code.

How are sentence coding questions solved?

Compare two sentences at a time and find the word they share; the code they share belongs to that word. Repeat with other pairs until only one code is left for the word you need.

Every question on this page is written and fact-checked by the GK Quizzes team. Spotted a mistake? Tell us and we will fix it. How we make our questions.