Coding and decoding is a pattern hunt, not a maths chapter. Everything here rests on one thing, and that is knowing the alphabet by number both forwards and backwards without counting on your fingers. Learn EJOTY and the opposite letter rule properly and you will read most codes in one look. When a question gives you a coded word, write the original letters in one row and the coded letters right below them, then check the gap letter by letter. The gap is a fixed shift, or it moves by one each time, or the word is simply reversed. If the code has numbers, first check the letter position, then check the sum of the letters, then check the number of letters. Test in that order and you will not waste time.
Coding-Decoding Rules and Shortcuts
Learn the alphabet positions cold
A=1, B=2, C=3, D=4, E=5, F=6, G=7, H=8, I=9, J=10, K=11, L=12, M=13
N=14, O=15, P=16, Q=17, R=18, S=19, T=20, U=21, V=22, W=23, X=24, Y=25, Z=26
EJOTY, the five letters that save you
E=5, J=10, O=15, T=20, Y=25
To find any letter fast, jump to the nearest one of these and count a step or two. For example, to find R, start at T=20 and go back two, so R=18.
Reverse position
Reverse position of a letter = 27 − Forward position
So A=26, B=25, M=14, N=13, Y=2, Z=1.
The opposite letter rule
Any letter and its opposite add up to 27.
A <-> Z, B <-> Y, C <-> X, D <-> W, E <-> V, F <-> U, G <-> T, H <-> S, I <-> R, J <-> Q, K <-> P, L <-> O, M <-> N
Learn the word CHUNK to place the middle: M and N sit at the centre, everything else mirrors around them.
Letter shift coding
Write the original word and the coded word one below the other and find the gap.
Fixed forward shift: CAT becomes DBU, every letter moves +1
Fixed backward shift: CAT becomes BZS, every letter moves −1
Increasing shift: the gap moves +1, +2, +3 letter by letter
Alternate shift: odd letters move forward, even letters move backward
Remember the alphabet wraps around, so Z + 1 = A and A − 1 = Z.
Reverse order coding
The whole word is written backwards: DELHI becomes IHLED
Or each half is reversed separately, or the letters are swapped in pairs: DELHI becomes EDHIL
Check reversal first, it is the most common trick and it takes two seconds to rule out.
Number coding
Check these three in order.
One, the letter position: DOG becomes 4-15-7
Two, the sum of the positions: DOG becomes 26
Three, the count of letters or a fixed operation on it, such as position × 2 or position + 3
If none fit, check position × number of letters, or the sum divided by the letter count.
Substitution coding
The word simply stands for something else. Sky is called sea, sea is called water, water is called air. If the question asks where a fish lives, the answer is not sea, it is what sea has been renamed to. Write the pairs down before you answer.
Mixed letter coding, the message type
When you get two or three coded sentences, find the word that is common to two sentences and the code that is common to the same two sentences. That code belongs to that word. Cancel out one word at a time.
Conditional coding
The paper gives a set of conditions and then asks you to code a group. Apply the conditions in the exact order written and check every condition before you mark. Marks are lost here only because students apply just the first condition and stop.
Symbol and figure coding
Each letter is fixed to a symbol. Build the key first, then translate. Do not try to guess the pattern, there usually is not one.
60 Coding-Decoding Reasoning Questions and Answers (Solved MCQs)
Question 1. In a certain code, TRAIN is written as USBJO. How is PLANE written in that code?
a) QMBOF
b) QMBNF
c) PMBOF
d) RMBOF
Answer:
a) QMBOF — Each letter is replaced by the next letter of the alphabet: P->Q, L->M, A->B, N->O and E->F.
Question 2. If MARKET is coded as LZQJDS, how is SCHOOL coded in the same way?
a) RBGNNK
b) RBGNMK
c) TDI PPM
d) RCFNNK
Answer:
a) RBGNNK — Each letter is replaced by the preceding letter: S->R, C->B, H->G, O->N, O->N and L->K.
Question 3. In a code language, DELHI is written as EFMIJ. How will KOLKATA be written?
a) LPMLBUB
b) LPMKBUB
c) LPNLBUB
d) KPNLBTA
Answer:
a) LPMLBUB — Every letter is moved one step forward: K->L, O->P, L->M, K->L, A->B, T->U and A->B.
Question 4. If TABLE is coded as GZYOV using the reverse alphabet system, how is CHAIR coded?
a) XSZRI
b) XSZIR
c) WRZRI
d) XTZRI
Answer:
a) XSZRI — In the reverse alphabet code, A↔Z, B↔Y, C↔X and so on. Therefore C->X, H->S, A->Z, I->R and R->I.
Question 5. In a certain code, MANGO is written as NZOHF. How is GRAPE written?
a) HQBQF
b) HQZQF
c) HSBQF
d) GQZQF
Answer:
b) HQZQF — Letters in odd positions move one step forward, while letters in even positions move one step backward: G->H, R->Q, A->B, P->O and E->F. Therefore the correct code should be HQBOF. None of the given options matches exactly.
Question 6. If BRIGHT is coded as DTKIJV, how is CLOUD coded?
a) ENQWF
b) ENQXF
c) DMPVE
d) ENPVF
Answer:
a) ENQWF — Each letter is shifted two places forward: C->E, L->N, O->Q, U->W and D->F.
Question 7. In a code, FRIEND is written as EQHDMC. How is PLANET written?
a) OKZMDQ
b) OKZODS
c) QMBODU
d) OKZMDS
Answer:
d) OKZMDS — Each letter is replaced by the previous letter: P->O, L->K, A->Z, N->M, E->D and T->S.
Question 8. If GARDEN is coded as AGDRNE, how is MARKET coded using the same pattern?
a) AMKRTE
b) AMKR ET
c) AMRAKT
d) MRAKTE
Answer:
a) AMKRTE — The letters are interchanged in adjacent pairs: GA->AG, RD->DR and EN->NE. Thus MA->AM, RK->KR and ET->TE.
Question 9. In a certain code, COMPUTER is written as RFUVQNPC. How is PRINTER written?
a) SFUOJSP
b) SFUOJSQ
c) RETNI RP
d) QSJOUFS
Answer:
a) SFUOJSP — First reverse the word PRINTER to RETNIRP, then move each letter one step forward: R->S, E->F, T->U, N->O, I->J, R->S and P->Q. Therefore the correct code is SFUOJSQ, which is option b.
Question 10. If MOBILE is coded as OQDKNG, how is CAMERA coded?
a) ECOGTC
b) ECPGTC
c) DBNFSB
d) ECOHUC
Answer:
a) ECOGTC — Each letter is shifted two places forward: C->E, A->C, M->O, E->G, R->T and A->C.
Question 11. In a certain code, LANGUAGE is written as MZOHVZHF. How is COMPUTER written?
a) DPNQVUFS
b) XLOKF GVI
c) XLNKFGVI
d) BNL OTSQD
Answer:
c) XLNKFGVI — The code uses the reverse alphabet: C->X, O->L, M->N, P->K, U->F, T->G, E->V and R->I.
Question 12. If NATION is coded as OCSMSO, how is PEOPLE coded in the same code?
a) QDPOMD
b) QFQOMF
c) QGQPMF
d) ODNOJD
Answer:
b) QFQOMF — Letters in odd positions move one step forward, and letters in even positions move one step backward: P->Q, E->D, O->P, P->O, L->M and E->D. Therefore the exact code is QDPOMD, which is option a.
Question 13. In a certain code, FLOWER is written as GKPVFQ. How is GARDEN written?
a) HZSCFM
b) HZQCFO
c) FZQCEM
d) HZQCFM
Answer:
d) HZQCFM — Letters in odd positions move one step forward and letters in even positions move one step backward: G->H, A->Z, R->S, D->C, E->F and N->M. Therefore the exact code is HZSCFM, which is option a.
Question 14. If MONDAY is coded as 13-15-14-4-1-25, how is FRIDAY coded?
a) 6-18-9-4-1-25
b) 6-17-9-4-1-25
c) 5-18-9-4-1-25
d) 6-18-8-4-1-25
Answer:
a) 6-18-9-4-1-25 — Each letter is replaced by its alphabetical position: F=6, R=18, I=9, D=4, A=1 and Y=25.
Question 15. In a certain code, EDUCATION is written as NOITACUDE. How is REASONING written?
a) GNINOSAER
b) GNINOSARE
c) GNINOSER
d) GNI NOSAER
Answer:
a) GNINOSAER — The word is written in reverse order. REASONING reversed is GNINOSAER.
Question 16. If CAT is coded as 24 and DOG is coded as 26, how is HEN coded?
a) 25
b) 26
c) 27
d) 28
Answer:
c) 27 — Add the alphabetical positions of the letters: H=8, E=5 and N=14. Therefore, 8+5+14=27.
Question 17. In a certain code, PEN is written as 16514. How is INK written in the same code?
a) 91411
b) 91511
c) 91412
d) 81511
Answer:
a) 91411 — Each letter is replaced by its alphabetical position: I=9, N=14 and K=11.
Question 18. If BOOK is coded as 2-15-15-11, how is PAGE coded?
a) 16-1-7-5
b) 15-1-7-5
c) 16-2-7-5
d) 16-1-8-5
Answer:
a) 16-1-7-5 — The letters are replaced by their positions in the English alphabet: P=16, A=1, G=7 and E=5.
Question 19. If APPLE is coded as 50, how is MANGO coded when the code is the sum of the alphabetical positions of its letters?
a) 48
b) 49
c) 50
d) 51
Answer:
c) 50 — M=13, A=1, N=14, G=7 and O=15. Their sum is 13+1+14+7+15=50.
Question 20. In a certain code, ROAD is written as 18-15-1-4. How is TRAIN written?
a) 20-18-1-9-14
b) 20-17-1-9-14
c) 19-18-1-9-14
d) 20-18-2-9-14
Answer:
a) 20-18-1-9-14 — T=20, R=18, A=1, I=9 and N=14.
Question 21. If BAD is coded as 7 and FACE is coded as 15, how is DEAF coded?
a) 14
b) 15
c) 16
d) 17
Answer:
c) 16 — The code is the sum of alphabetical positions: D=4, E=5, A=1 and F=6. Thus, 4+5+1+6=16.
Question 22. In a code language, 123 means “hot tea ready”, 356 means “tea is sweet” and 248 means “hot food available”. Which digit represents “hot”?
a) 1
b) 2
c) 3
d) 8
Answer:
a) 1 — The common word in the first and third statements is “hot”, and the common digit is 2? Comparing 123 and 248, the common digit is 2. Therefore, the correct answer is b) 2.
Question 23. In a certain code language, “red blue green” is written as “ka ti mo”, “blue white black” as “ti na su” and “green yellow white” as “mo pa na”. What is the code for “white”?
a) ka
b) ti
c) mo
d) na
Answer:
d) na — “White” appears in the second and third statements, and the common code in those statements is “na”.
Question 24. In a certain code language, “books are useful” is coded as “li pa no”, “pens are costly” as “ta pa mi” and “useful things last” as “no su ke”. What is the code for “are”?
a) li
b) pa
c) no
d) mi
Answer:
b) pa — “Are” is common to the first and second statements, and “pa” is the common code.
Question 25. If A=1, B=2, C=3 and so on, what is the difference between the codes of MATH and PATH?
a) 1
b) 2
c) 3
d) 4
Answer:
c) 3 — MATH=13+1+20+8=42 and PATH=16+1+20+8=45. Difference=45−42=3.
Question 26. If the code of a word is obtained by multiplying the alphabetical positions of its first and last letters, what is the code for TABLE?
a) 80
b) 90
c) 100
d) 120
Answer:
c) 100 — The first letter is T=20 and the last letter is E=5. Therefore, 20×5=100.
Question 27. If HOUSE is coded as 8-15-21-19-5 and the numbers are then added, what is the final code?
a) 66
b) 67
c) 68
d) 69
Answer:
c) 68 — H=8, O=15, U=21, S=19 and E=5. Their total is 8+15+21+19+5=68.
Question 28. In a code language, “bring fresh water” is written as “zo ki pa”, “fresh fruits daily” as “ki la ne” and “bring fruits home” as “zo la mu”. What is the code for “fruits”?
a) zo
b) ki
c) la
d) mu
Answer:
c) la — “Fruits” is common to the second and third statements, and “la” is the common code.
Question 29. In a certain code, ‘+’ means ‘÷’, ‘−’ means ‘×’, ‘×’ means ‘+’ and ‘÷’ means ‘−’. What is the value of 18 + 3 − 4?
a) 20
b) 24
c) 28
d) 30
Answer:
b) 24 — Replace the symbols according to the code: 18 ÷ 3 × 4. Following the order of operations, 18÷3=6 and 6×4=24.
Question 30. If ‘P × Q’ means ‘P is the mother of Q’, ‘P + Q’ means ‘P is the brother of Q’ and ‘P − Q’ means ‘P is the father of Q’, which expression means “A is the maternal uncle of B”?
a) A + C × B
b) A − C × B
c) A × C + B
d) A + C − B
Answer:
a) A + C × B — A+C means A is the brother of C, and C×B means C is the mother of B. Therefore, A is the brother of B’s mother, making A the maternal uncle of B.
Question 31. In a certain code language, “smart students learn quickly” is written as “ka lo mi tu”, “students solve questions quickly” is written as “lo pa se tu” and “smart people solve problems” is written as “ka ri pa no”. What is the code for “solve”?
a) ka
b) lo
c) pa
d) tu
Answer:
c) pa — “Solve” is common to the second and third statements, and “pa” is the common code.
Question 32. In a certain code language, “good food gives energy” is coded as “na ki ro se”, “fresh food tastes good” as “pa ki lu na” and “energy improves health” as “se mi jo”. What is the code for “good”?
a) na
b) ki
c) se
d) lu
Answer:
a) na — “Good” and “food” are common to the first two statements. Their common codes are “na” and “ki”. Since “food” is represented by “ki”, “good” is represented by “na”.
Question 33. If MOBILE is coded as 13-30-4-18-24-10, how is CAMERA coded using the same rule?
a) 6-2-26-10-36-2
b) 6-2-24-10-36-2
c) 3-1-13-5-18-1
d) 6-4-26-10-36-4
Answer:
a) 6-2-26-10-36-2 — Each letter’s alphabetical position is multiplied by 2: C=3×2=6, A=1×2=2, M=13×2=26, E=5×2=10, R=18×2=36 and A=1×2=2.
Question 34. In a certain code, BRIGHT is written as 2-36-9-14-8-40. How is CLOUD written?
a) 3-24-15-42-4
b) 6-24-30-42-8
c) 6-12-30-21-8
d) 3-12-15-21-4
Answer:
b) 6-24-30-42-8 — Letters in odd positions are doubled and letters in even positions are also doubled: C=3×2=6, L=12×2=24, O=15×2=30, U=21×2=42 and D=4×2=8.
Question 35. If the letters of the word MARKET are arranged in reverse order and then each letter is moved one step forward, what will be the code?
a) UFLSBN
b) UFLRBN
c) TFJQAM
d) VGMTCO
Answer:
a) UFLSBN — MARKET reversed is TEKRAM. Moving each letter one step forward gives U, F, L, S, B, N.
Question 36. In a certain code, DELHI is written as 4-5-12-8-9 and INDIA is written as 9-14-4-9-1. If the code of a word is the sum of its letter values, what is the code of KERALA?
a) 44
b) 46
c) 48
d) 50
Answer:
c) 48 — K=11, E=5, R=18, A=1, L=12 and A=1. Total = 11+5+18+1+12+1=48.
Question 37. In a certain code language, “work hard for success” is written as “di ka mo se”, “hard work brings results” as “ka di pu la” and “success brings happiness” as “se pu no”. What is the code for “results”?
a) ka
b) di
c) la
d) pu
Answer:
c) la — “Work” and “hard” are represented by “di” and “ka”, while “brings” is represented by “pu”. Therefore, the remaining code “la” represents “results”.
Question 38. If A=26, B=25, C=24 and so on, what is the code value of DOG?
a) 54
b) 56
c) 58
d) 60
Answer:
b) 56 — In reverse alphabetical values, D=23, O=12 and G=20. Therefore, 23+12+20=55? Rechecking: A=26 means D=23, O=12 and G=20, so the correct total is 55. None of the options is correct.
Question 39. If in a code language, MONKEY is written as XDJMNL, how will TIGER be written using the same pattern?
a) QDFHS
b) QEHJS
c) SFHJU
d) QDFIT
Answer:
a) QDFHS — Reverse MONKEY to YEKNOM and move each letter one step backward to get XDJMNL. Similarly, TIGER reversed is REGIT; moving each letter one step backward gives QDFHS.
Question 40. In a certain code, the first and last letters of a word are interchanged, then the second and second-last letters are interchanged, and so on. How is EDUCATION coded?
a) NOITACUDE
b) NOITAU CDE
c) NOUTACIDE
d) NOITACDUE
Answer:
a) NOITACUDE — The described operation reverses the entire word. EDUCATION reversed is NOITACUDE.
Question 41. In a certain code language, “milk is good” is written as “pa lo ki”, “good food is healthy” as “ki su lo na” and “healthy milk gives strength” as “na pa re tu”. What is the code for “is”?
a) pa
b) lo
c) ki
d) na
Answer:
b) lo — “Milk” is represented by “pa”, “good” by “ki” and “healthy” by “na”. Therefore, the remaining common code “lo” represents “is”.
Question 42. If COMPUTER is coded by replacing each letter with the letter two positions ahead in the alphabet, what is the code for KEYBOARD?
a) MGA DQCTF
b) MGA DQCTF
c) MGADQCTF
d) LFZCPBSE
Answer:
c) MGADQCTF — K->M, E->G, Y->A, B->D, O->Q, A->C, R->T and D->F.
Question 43. If the code of a word is obtained by adding the alphabetical positions of its vowels and subtracting the positions of its consonants, what is the code of ACE?
a) 7
b) 8
c) 9
d) 10
Answer:
c) 9 — A and E are vowels, while C is a consonant. Therefore, code = 1+5−3=3? Since ACE contains A, C and E, the correct value is 3. None of the options is correct.
Question 44. In a certain code language, “read books daily” is written as “ma ki lo”, “books improve knowledge” as “ki pa se” and “daily practice improves skill” as “lo tu pa na”. What is the code for “improves”?
a) ki
b) lo
c) pa
d) se
Answer:
c) pa — “Improve” and “improves” are treated as the same coded idea. It is common to the second and third statements, and “pa” is the common code.
Question 45. If “P + Q” means “P is the father of Q”, “P − Q” means “P is the sister of Q”, “P × Q” means “P is the brother of Q” and “P ÷ Q” means “P is the mother of Q”, which expression means “A is the paternal aunt of B”?
a) A − C + B
b) A ÷ C + B
c) A × C + B
d) A − C ÷ B
Answer:
a) A − C + B — A−C means A is the sister of C, and C+B means C is the father of B. Therefore, A is the sister of B’s father, making A the paternal aunt of B.
Question 46. In a certain code, each letter in an odd position is moved two places forward and each letter in an even position is moved one place backward. How is MARKET coded?
a) OZTDGS
b) OZTJGS
c) NZTDGS
d) OYTDGR
Answer:
a) OZTDGS — M->O, A->Z, R->T, K->J, E->G and T->S.
Question 47. If COMPUTER is coded as DQNTVSDQ, how is KEYBOARD coded using the same pattern?
a) LDXAPZSC
b) LFXCPZSC
c) LDXBOZSC
d) KDXAPZRC
Answer:
a) LDXAPZSC — Letters in odd positions move one step forward and letters in even positions move one step backward: K->L, E->D, Y->Z? Applying the pattern carefully gives K->L, E->D, Y->Z, B->A, O->P, A->Z, R->S and D->C, producing LDZAPZSC. Therefore, the intended correct code should be LDZAPZSC.
Question 48. In a certain code, the alphabetical position of each letter is doubled and then 1 is added. What is the code for FACE?
a) 13-3-7-11
b) 13-5-7-11
c) 12-3-6-10
d) 11-3-7-9
Answer:
a) 13-3-7-11 — F=6 gives 2×6+1=13, A=1 gives 3, C=3 gives 7 and E=5 gives 11.
Question 49. In a certain code language, “bright stars shine” is written as “ka mi zo”, “stars appear nightly” as “mi pa tu” and “bright lights appear” as “ka se pa”. What is the code for “shine”?
a) ka
b) mi
c) zo
d) se
Answer:
c) zo — “Bright” is coded as “ka” and “stars” as “mi”. Therefore, the remaining code “zo” represents “shine”.
Question 50. If the first half of a word is reversed and the second half is also reversed separately, how is NOTEBOOK coded?
a) ETONKOOB
b) TONEBOOK
c) ETONBOOK
d) NOTEKOOB
Answer:
a) ETONKOOB — NOTEBOOK is divided into NOTE and BOOK. Reversing each part separately gives ETON and KOOB.
Question 51. In a certain code, A=2, B=6, C=12, D=20 and so on. What is the code value of F?
a) 30
b) 36
c) 42
d) 48
Answer:
c) 42 — The pattern is n(n+1), where n is the alphabetical position. For F, n=6, so 6×7=42.
Question 52. If TRAIN is coded as 20-16-4-13-19, how is PLANE coded using the same rule?
a) 17-10-5-11-10
b) 17-10-5-13-10
c) 16-12-1-14-5
d) 18-11-6-14-11
Answer:
b) 17-10-5-13-10 — Each letter’s alphabetical position is increased by 1 for odd-positioned letters and decreased by 2 for even-positioned letters: P=16+1=17, L=12−2=10, A=1+1=2? Since this gives 17-10-2-12-6, the options do not match the stated rule.
Question 53. In a code language, “honesty brings respect” is written as “lo ka mi”, “respect earns trust” as “mi pa se” and “honesty earns success” as “lo pa tu”. What is the code for “brings”?
a) lo
b) ka
c) mi
d) pa
Answer:
b) ka — “Honesty” is represented by “lo” and “respect” by “mi”. Therefore, the remaining code “ka” represents “brings”.
Question 54. If the code of a word is obtained by multiplying the sum of the vowel positions by the number of consonants, what is the code of MOBILE?
a) 60
b) 72
c) 84
d) 96
Answer:
b) 72 — The vowels are O=15, I=9 and E=5, whose sum is 29. There are three consonants. Thus, 29×3=87. Therefore, none of the options is correct.
Question 55. If every consonant is replaced by the next consonant and every vowel by the previous vowel in the sequence A, E, I, O, U, how is TABLE coded?
a) VUCMI
b) VUCMA
c) VEBMI
d) SUCMI
Answer:
a) VUCMI — T->V, A->U, B->C, L->M and E->A? Therefore, the exact code should be VUCMA.
Question 56. In a certain code, PLANET is written as 16-24-3-56-25-120. What is the code for MANGO?
a) 13-2-42-28-75
b) 13-2-42-28-60
c) 26-2-42-28-75
d) 13-1-14-7-15
Answer:
a) 13-2-42-28-75 — Each letter’s alphabetical position is multiplied by its position in the word: M=13×1, A=1×2, N=14×3, G=7×4 and O=15×5.
Question 57. In a certain code, SCHOOL is written as TDIPPM. How is MARKET written?
a) NBSLFU
b) NBSMFU
c) NBRLFU
d) OBTLFV
Answer:
a) NBSLFU — Each letter is moved one place forward: M->N, A->B, R->S, K->L, E->F and T->U.
Question 58. In a code language, “blue sky looks beautiful” is written as “na ki po se”, “beautiful flowers look fresh” as “se tu po ma” and “blue flowers bloom” as “na tu ra”. What is the code for “looks”?
a) na
b) ki
c) po
d) se
Answer:
c) po — “Beautiful” is coded as “se”, “blue” as “na” and “flowers” as “tu”. Therefore, “po” represents “looks” or “look”.
Question 59. If “A @ B” means “A is the son of B”, “A # B” means “A is the wife of B” and “A $ B” means “A is the brother of B”, which expression shows that P is the nephew of Q?
a) P @ R $ Q
b) P $ R @ Q
c) P @ R # Q
d) P # R $ Q
Answer:
a) P @ R $ Q — P@R means P is the son of R, and R$Q means R is the brother of Q. Therefore, P is the son of Q’s brother and hence Q’s nephew.
Question 60. In a certain code, each letter is replaced by its reverse-alphabet equivalent, and the resulting word is then reversed. How is LOGIC coded?
a) XRTLO
b) XRTOL
c) CIGOL
d) ORTXL
Answer:
a) XRTLO — Reverse-alphabet equivalents of L, O, G, I and C are O, L, T, R and X. Reversing OLTRX gives XRTLO.
