Practice a wide variety of mental ability test questions on coding–decoding for class 4. Start with easy patterns and level up to very tough multi-step logic. Each answer includes a short explanation.
Easy Level (15 Questions) Mental Ability Coding-Decoding Question for Class 4
Letter Shift (+1)
Question 1. If CAT = DBU, then DOG = ?
a) EPH
b) DPF
c) EOH
d) FPH
Answer:
a) EPH — Each letter +1: D→E, O→P, G→H.
Word Substitution
Question 2. If ‘Pen’ is called ‘Book’, ‘Book’ is called ‘Paper’, and ‘Paper’ is called ‘Ink’, which is used to write?
a) Ink
b) Book
c) Paper
d) Pen
Answer:
b) Book — We write with a Pen, which is called ‘Book’.
Alphabet Positions
Question 3. Using A=1, B=2, …, Z=26, the code for RISHI is:
a) 18-9-19-8-9
b) 19-18-8-9-19
c) 18-9-8-19-9
d) 18-19-9-8-9
Answer:
a) 18-9-19-8-9 — R(18) I(9) S(19) H(8) I(9).
Reverse Word
Question 4. If FLOWER is written as REWOLF, how is GARDEN written?
a) NEDRAG
b) DENGAR
c) NEDGAR
d) GARDNE
Answer:
a) NEDRAG — Reverse the letters.
Letter Shift (+1)
Question 5. If LION = MJPO, then BEAR = ?
a) CFBS
b) CGAS
c) CFBQ
d) CFBS
Answer:
a) CFBS — +1: B→C, E→F, A→B, R→S.
Sentence Substitution
Question 6. If ‘Sky’ means ‘Ground’, ‘Ground’ means ‘Sea’, and ‘Sea’ means ‘Air’, where do airplanes fly?
a) Ground
b) Air
c) Sky
d) Sea
Answer:
d) Sea — Air is called ‘Sea’.
Sum of Positions
Question 7. APPLE is coded as 50 (sum of letter positions). What is the code for GRAPE?
a) 47
b) 46
c) 52
d) 55
Answer:
a) 47 — 7+18+1+16+5 = 47.
Symbol Mapping
Question 8. If A=★, B=☆, C=♣, D=♠, then BAD is coded as:
a) ☆★♠
b) ★☆♠
c) ☆♠★
d) ♠☆★
Answer:
a) ☆★♠ — B=☆, A=★, D=♠.
Positions
Question 9. ‘MANGO’ is coded as ’13-1-14-7-15′. How is ‘APPLE’ coded?
a) 1-16-16-12-5
b) 1-15-16-12-5
c) 1-16-15-12-5
d) 11-3-19-12-5
Answer:
a) 1-16-16-12-5 — A(1) P(16) P(16) L(12) E(5).
Direct Positions
Question 10. In a code, CLASS is 3-12-1-19-19. How is SCHOOL written?
a) 19-3-8-15-15-12
b) 18-3-8-15-15-12
c) 19-4-8-16-16-12
d) 19-3-7-15-15-12
Answer:
a) 19-3-8-15-15-12 — S C H O O L.
Reverse Letters
Question 11. If SCHOOL → LOOCSH, then GAMES → ?
a) SEMAG
b) SEAMG
c) SGEAM
d) SEMA G
Answer:
a) SEMAG — Reverse the word.
Skip-1 Pick
Question 12. Write every second letter of ELEPHANT starting from the first.
a) EEA
b) ELHT
c) ELPHT
d) EEA T
Answer:
b) ELHT — E(1), L(3), H(5), T(7).
Mirror (Atbash)
Question 13. Using mirror positions (A↔Z, B↔Y, …), the mirror of DOG is:
a) WLT
b) WLR
c) WOL
d) WLV
Answer:
a) WLT — D→W, O→L, G→T.
Count Vowels
Question 14. Code equals number of vowels in the word. For ORANGE, code is:
a) 2
b) 3
c) 4
d) 1
Answer:
b) 3 — O, A, E.
Telephone Keypad
Question 15. Using keypad (ABC=2, DEF=3, GHI=4, JKL=5, MNO=6, PQRS=7, TUV=8, WXYZ=9), code for CAT is:
a) 222
b) 228
c) 248
d) 242
Answer:
b) 228 — C(2) A(2) T(8).
Medium Level (15 Questions) Mental Ability Coding-Decoding Question for Class 4
Letter Shift (-1)
Question 16. If ZEBRA becomes YDAQZ, then LEMON becomes:
a) KDLNM
b) KDKMN
c) KDLNL
d) KDLNM
Answer:
a) KDLNM — Each letter −1.
Odd–Even Pair Swap
Question 17. Swap letters in pairs: COMPUTER → ?
a) OCMPUTRE
b) OCMPUERT
c) OCPMOUTE
d) OCMPOETU
Answer:
a) OCMPUTRE — CO→OC, MP→PM, UT→TU, ER→RE → OC PM TU RE.
Position Difference
Question 18. For two letters XY, code is |pos(X)−pos(Y)|. For HM the code is:
a) 6
b) 5
c) 4
d) 3
Answer:
b) 5 — |8−13| = 5.
Reverse + Shift (+1)
Question 19. Code = reverse the word, then shift each letter +1. For BAT:
a) UBC
b) CBU
c) UCB
d) CBV
Answer:
a) UBC — BAT → TAB → UBC.
Odd-Position Extract
Question 20. Pick letters at odd positions from NOTEBOOK.
a) NTEO
b) NTEOK
c) NTOO
d) NTEK
Answer:
a) NTEO — Positions 1,3,5,7.
Count Consonants
Question 21. Code equals number of consonants. For TIGER, code is:
a) 2
b) 3
c) 4
d) 5
Answer:
b) 3 — T, G, R.
Split & Reverse Halves
Question 22. Split NOTEBOOK into NOTE and BOOK, reverse each, then join.
a) ETONKOOB
b) ETONBOOk
c) ETONKO OB
d) ETO NKOOB
Answer:
a) ETONKOOB.
Word Substitution (Places)
Question 23. If ‘School’ is ‘Garden’, ‘Garden’ is ‘Library’, ‘Library’ is ‘Home’, where do children study?
a) Library
b) Home
c) School
d) Garden
Answer:
a) Library — School→Garden→Library.
Mirror + Reverse
Question 24. Take mirror letters (A↔Z, …) then reverse. Code of CAT is:
a) GZX
b) XZG
c) XZB
d) GXZ
Answer:
a) GZX — C→X, A→Z, T→G → reverse = G Z X.
Sum of Positions
Question 25. Find sum of positions for SCHOOL.
a) 72
b) 73
c) 74
d) 76
Answer:
a) 72 — 19+3+8+15+15+12=72.
Even-Position Shift (+2)
Question 26. For SCHOOL, add +2 to even positions only (positions from 1).
a) S E I Q O N
b) S E I Q O N (spaces optional)
c) S E H Q O N
d) S D I Q O N
Answer:
a) S E I Q O N — 1:S, 2:C→E, 3:H, 4:O→Q, 5:O, 6:L→N.
Letter Shift Pattern (+2, −1, +2, −1, …)
Question 27. Apply +2, −1, +2, −1, … on APPLE.
a) CORKG
b) CORKD
c) BORKG
d) CONKG
Answer:
a) CORKG — A→C, P→O, P→R, L→K, E→G.
Two-Word Positions
Question 28. BOY = 2-15-25 and GIRL = 7-9-18-12. CHILD is:
a) 3-8-9-12-4
b) 3-9-8-12-4
c) 3-8-9-11-4
d) 3-7-9-12-4
Answer:
a) 3-8-9-12-4 — C H I L D.
Sum vs Product
Question 29. For a 3-letter word XYZ, code is (X+Y+Z, X×Y×Z). For CAT the pair is:
a) (24, 60)
b) (23, 60)
c) (24, 45)
d) (25, 60)
Answer:
a) (24, 60) — 3+1+20=24; 3×1×20=60.
Positions (Direct)
Question 30. Code for DOG is:
a) 4-15-7
b) 4-16-7
c) 5-15-7
d) 5-16-7
Answer:
a) 4-15-7 — D O G.
Tough Level (15 Questions) Mental Ability Coding-Decoding Question for Class 4
Alternate Shift (Odd +1, Even −1)
Question 31. Apply: odd positions +1, even positions −1 on TIGER.
a) UHFDS
b) UJFDQ
c) UHFDR
d) UHF DQ
Answer:
a) UHFDS — T→U, I→H, G→H, E→D, R→S.
Reverse Every Pair
Question 32. Reverse each pair of letters in ELEPHANT (EL)(EP)(HA)(NT).
a) LEPEAHNT
b) LEPEAH TN
c) LEPEAHNT (spaces optional)
d) LEEPHA NT
Answer:
a) LEPEAHNT — EL→LE, EP→PE, HA→AH, NT→TN.
Mirror (Whole Word)
Question 33. Mirror code (A↔Z) of BEAR:
a) YVZI
b) YVZI (no spaces)
c) YVZI (same)
d) YWZI
Answer:
a) YVZI — B→Y, E→V, A→Z, R→I.
Reverse + Mirror
Question 34. Reverse word then mirror letters. For LATE:
a) OZIG
b) OZIR
c) OZGV
d) OZGV (same)
Answer:
c) OZGV — LATE→ETAL; E→V, T→G, A→Z, L→O → V G Z O → reversed order from step = OZGV.
Paired-End Sums
Question 35. For LEMON, add L+N and E+O (ignore middle M). Give pair:
a) (26, 20)
b) (25, 20)
c) (26, 19)
d) (27, 20)
Answer:
a) (26, 20) — 12+14=26; 5+15=20.
Index-Weighted Sum
Question 36. Value = Σ[i×pos(letter_i)], i from 1. For CAT:
a) 65
b) 60
c) 63
d) 58
Answer:
a) 65 — 1×3 + 2×1 + 3×20 = 3 + 2 + 60.
Vowel-Next, Consonant-Prev
Question 37. Replace vowels by next vowel (A→E, E→I, I→O, O→U, U→A) and consonants by previous letter. For NOTE:
a) MU SI
b) MUSI
c) NUSI
d) MTSI
Answer:
b) MUSI — N→M, O→U, T→S, E→I.
Extract Even Positions
Question 38. Take letters at even positions of STRAWBERRY.
a) TABRY
b) TRWER
c) TARBY
d) TARRY
Answer:
a) TABRY — Positions 2,4,6,8,10 → T, A, B, R, Y.
Block Shift
Question 39. Split ELEPHANT into ELEP and HANT; shift first block +1 and second block −1.
a) FMFQGZMS
b) FMFQGAMS
c) FMFQHZMS
d) FNFQGZMS
Answer:
a) FMFQGZMS — ELEP→FMFQ; HANT→GZMS.
Positions Sum to Target
Question 40. Which word has sum of positions = 33?
a) BANANA
b) PEACH
c) KIWI
d) PEAR
Answer:
a) BANANA — 2+1+14+1+14+1 = 33.
Double Shift (+1 then +2)
Question 41. Shift first two letters of MINT by +1, remaining by +2.
a) N J P V
b) N J P U
c) NJPV
d) NJPU
Answer:
c) NJPV — M→N, I→J, N→P, T→V.
Mirror at Odd, +1 at Even
Question 42. For TIGER, mirror odd positions, add +1 to even positions.
a) GJTFI
b) GJTFH
c) GHTFI
d) GJTEI
Answer:
a) GJTFI — T→G, I→J, G→T, E→F, R→I.
Sum of First & Last Only
Question 43. For STARS, code = pos(first)+pos(last). What is it?
a) 38
b) 37
c) 39
d) 36
Answer:
a) 38 — S(19)+S(19)=38.
Replace by Previous
Question 44. Replace each letter by the previous one. For MOUSE:
a) L N T R D
b) LNT RD
c) LNTRD
d) LO TRD
Answer:
c) LNTRD — M→L, O→N, U→T, S→R, E→D.
Reverse Middle Only
Question 45. For 5-letter words ABCDE, reverse only BCD. For PLANT:
a) P L A N T (no change)
b) P A L N T
c) P A L N T (same as b)
d) P N L A T
Answer:
b) PALNT — BCD = LAN → reversed = NAL → P N A L T, but positions keep A in middle: P A L N T. (PALNT)
Very Tough Level (5 Questions) Mental Ability Coding-Decoding Question for Class 4
Two-Step Mirror-Shift
Question 46. Take mirror letter (A↔Z) then shift +1. Code for BAG is:
a) ZAU
b) YAU
c) ZAV
d) ZBU
Answer:
a) ZAU — B→Y→Z, A→Z→A, G→T→U → Z A U.
Chain Substitution
Question 47. If ‘Rain’ is ‘Sun’, ‘Sun’ is ‘Cloud’, ‘Cloud’ is ‘Wind’, then what falls from the sky?
a) Sun
b) Cloud
c) Wind
d) Rain
Answer:
a) Sun — Rain falls; Rain is called ‘Sun’.
Three-Step Mix
Question 48. Steps: (i) reverse word, (ii) vowels → next vowel, (iii) consonants −1. For NOTE:
a) ISMU
b) I SMU
c) ISMV
d) ISNU
Answer:
a) ISMU — NOTE→ETON; vowels: E→I, O→U; consonants: T→S, N→M → I S M U.
Index Math
Question 49. Value = Σ[i×pos(letter_i)] for DOG.
a) 55
b) 56
c) 57
d) 58
Answer:
a) 55 — 1×4 + 2×15 + 3×7 = 4 + 30 + 21.
Alternating Mirror
Question 50. For TIGER, mirror odd positions and keep even positions unchanged.
a) G I T E I
b) G I T E R
c) G I T E H
d) G H T E I
Answer:
a) G I T E I — T→G, I→I, G→T, E→E, R→I.
