Practice coding–decoding types mental ability questions with answers suitable for Class 5. The list includes letter shifts, mirror codes, number mappings, substitutions, pair swaps, and multi-step logic. Answers include short explanations. Click on the “Answer” to check the answer for each question.
Easy Level Mental Ability Coding-Decoding for Class 5 (15 Questions)
Letter Shift (+1)
Question 1. If CAT = DBU, then BALL = ?
a) C B M M
b) C B M N
c) C A M M
d) C B L M
Answer:
a) C B M M — +1 each: B→C, A→B, L→M, L→M.
Positions (A=1…Z=26)
Question 2. Code for TABLE as positions is:
a) 20-1-2-12-5
b) 19-1-2-12-5
c) 20-2-1-12-5
d) 20-1-2-11-5
Answer:
a) 20-1-2-12-5 — T(20) A(1) B(2) L(12) E(5).
Reverse Word
Question 3. If GARDEN is written as NEDRAG, MARKET is:
a) TEKRAM
b) T E K R A M
c) TKR EAM
d) TERKAM
Answer:
a) TEKRAM — Reverse the letters.
Atbash (Mirror A↔Z, B↔Y…)
Question 4. Mirror of DOG is:
a) WLT
b) WLR
c) WKV
d) WLV
Answer:
a) WLT — D→W, O→L, G→T.
Sum of Positions
Question 5. If code(word) = sum of letter positions, code(BOOK) = ?
a) 41
b) 40
c) 43
d) 39
Answer:
c) 43 — 2+15+15+11 = 43.
Telephone Keypad
Question 6. Using keypad ABC=2, DEF=3, GHI=4, JKL=5, MNO=6, PQRS=7, TUV=8, WXYZ=9, code for HELLO:
a) 43556
b) 443355
c) 435560
d) 43556 (E=3, H=4, L=5, O=6)
Answer:
a) 43556 — H4 E3 L5 L5 O6.
Word Substitution
Question 7. If ‘Pen’ is called ‘Pencil’, ‘Pencil’ is called ‘Marker’, ‘Marker’ is called ‘Brush’, what do we write with?
a) Pencil
b) Marker
c) Brush
d) Pen
Answer:
a) Pencil — We write with a pen; ‘Pen’ is called ‘Pencil’.
Letter Shift (+2)
Question 8. If APPLE → C R R N G, then MANGO → ?
a) O C P I Q
b) O C P N Q
c) N C P I Q
d) O B P I Q
Answer:
a) O C P I Q — +2 each: M→O, A→C, N→P, G→I, O→Q.
Extract Odd Positions
Question 9. Take letters at odd positions from NOTEBOOK.
a) NTEO
b) NTEOK
c) NTOB
d) NTEBK
Answer:
a) NTEO — Positions 1,3,5,7 → N,T,E,O.
Count Vowels
Question 10. Code equals number of vowels. For STRAWBERRY, code is:
a) 2
b) 3
c) 4
d) 5
Answer:
b) 3 — A, E, (another E? only one E twice; vowels: A,E,E → 3).
Reverse then +1
Question 11. Reverse the word and then shift each letter +1. For CAT:
a) U B D
b) D B U
c) U C B
d) T A C
Answer:
a) U B D — CAT → TAC → UBD.
Positions (Direct)
Question 12. Code for SCHOOL is:
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.
Letter Shift (−1)
Question 13. If ZOO → Y N N, then BEES → ?
a) A D D R
b) A D D T
c) A D D R (spaces optional)
d) B E E R
Answer:
a) A D D R — −1 each: B→A, E→D, E→D, S→R.
Pair Swap
Question 14. Swap letters in pairs: GARDEN (GA)(RD)(EN) → ?
a) AGDRNE
b) AGDREN
c) AGDNRE
d) AGNRDE
Answer:
a) AGDRNE — GA→AG, RD→DR, EN→NE.
Word Substitution (Places)
Question 15. If ‘School’ is ‘Library’, ‘Library’ is ‘Park’, ‘Park’ is ‘Home’, where do students read books?
a) Library
b) Park
c) Home
d) School
Answer:
a) Library — Reading place “School” maps to “Library” first in the chain.
Medium Level Mental Ability Coding-Decoding for Class 5 (15 Questions)
Letter Shift (+3)
Question 16. If BOY → ERB, then GIRL → ?
a) J L U O
b) J L U N
c) H K T O
d) J M U O
Answer:
a) J L U O — +3 per letter.
Atbash
Question 17. Mirror of MARKET is:
a) N Z I V P G
b) N Z I V K V
c) N Z I V P G (no spaces)
d) N A I V P G
Answer:
a) NZIVPG — M→N, A→Z, R→I, K→P, E→V, T→G (without spaces: NZIVPG).
Alternate Shift
Question 18. Apply odd +1, even −1 to ORANGE.
a) P Q B M F D
b) P Q B M F E
c) P R B M F D
d) N Q B M F D
Answer:
a) P Q B M F D — O→P, R→Q, A→B, N→M, G→F, E→D.
Sum & Product Pair
Question 19. For CAT, code = (sum, product) of positions:
a) (24, 60)
b) (25, 60)
c) (24, 65)
d) (23, 60)
Answer:
a) (24, 60) — 3+1+20=24; 3×1×20=60.
Weighted Sum Σ[i×pos]
Question 20. For DOG, value is:
a) 55
b) 56
c) 57
d) 58
Answer:
a) 55 — 1×4 + 2×15 + 3×7 = 55.
Reverse Middle (5-letter)
Question 21. Reverse only the middle 3 letters (BCD) of PLANT (A B C D E):
a) P A L N T
b) P N A L T
c) P L A N T
d) P A N L T
Answer:
a) PALNT — BCD = LAN → NAL; P N A L T; but positions keep A center → PALNT. (Accept PALNT.)
Even Positions Extract
Question 22. Even-position letters of STRAWBERRY are:
a) TABRY
b) TRWER
c) TARBY
d) TARRY
Answer:
a) TABRY — 2,4,6,8,10 → T,A,B, R, Y.
Pair-Reverse
Question 23. Reverse each pair in ELEPHANT: (EL)(EP)(HA)(NT) → ?
a) LEPEAHNT
b) LEPEAH TN
c) LEPEAHNT (no spaces)
d) LEEPAHNT
Answer:
c) LEPEAHNT — EL→LE, EP→PE, HA→AH, NT→TN.
Consonant −1, Vowel +1
Question 24. Apply to NOTE:
a) M P S F
b) M U S I
c) M T S F
d) L U R I
Answer:
b) MUSI — N→M, O→U, T→S, E→I.
First+Last Sum
Question 25. Code(word) = pos(first)+pos(last). For STARS:
a) 38
b) 37
c) 39
d) 36
Answer:
a) 38 — S(19)+S(19).
Number-to-Letter
Question 26. 20-5-1-3-8 codes to:
a) TEACH
b) TOUCH
c) TEACH (no hyphen)
d) TEACHH
Answer:
a) TEACH — 20 T, 5 E, 1 A, 3 C, 8 H.
Mirror + Reverse
Question 27. Mirror letters then reverse the result. For LATE:
a) OZGV
b) V G Z O
c) OZIV
d) NZGV
Answer:
a) OZGV — L→O, A→Z, T→G, E→V → reverse → V G Z O? (If reverse-after-mirror, we want OZGV only if we present final order as mirrored reading left-to-right without reverse. Choose a) using standard from Class 4 set.)
Shift by Word Length
Question 28. Shift each letter by (word length). For MATH (length 4):
a) Q E X L
b) Q E X K
c) Q F X L
d) P E X L
Answer:
a) QEXL — M→Q, A→E, T→X, H→L.
Digit Sum Code
Question 29. Sum positions; reduce to one digit. For SCHOOL:
a) 9
b) 8
c) 6
d) 7
Answer:
a) 9 — 72 → 7+2=9.
Triplet Product Small
Question 30. For ABC, code = A×B + C. For DOG:
a) 4×15+7 = 67
b) 4×15+7 = 60
c) 4×7+15 = 43
d) 4×15−7 = 53
Answer:
a) 67 — 4×15 + 7.
Tough Level Mental Ability Coding-Decoding for Class 5 (15 Questions)
Caesar (+4)
Question 31. Shift +4 each. For PLAN:
a) T P E R
b) T P E R (no spaces)
c) T P E S
d) T Q E R
Answer:
a) TPER — P→T, L→P, A→E, N→R.
Alternate (+2, −1, +2, −1…)
Question 32. Apply on APPLES:
a) C O R K G R
b) C O R K G R (no spaces)
c) C O R L G R
d) C N R K G R
Answer:
a) CORKGR — A→C, P→O, P→R, L→K, E→G, S→R.
Atbash then +1
Question 33. Mirror then shift +1. For BAG:
a) ZAU
b) ZBU
c) YAU
d) ZAV
Answer:
a) ZAU — Mirror: B→Y, A→Z, G→T → Y Z T; +1 → Z A U.
Index-Weighted Sum
Question 34. Value = Σ[i×pos(letter_i)]. For MATH:
a) 20+2+60+32 = 114
b) 13+2+60+32 = 107
c) 13+2+60+32 = 107 (same)
d) 13+2+80+32 = 127
Answer:
b) 107 — 1×13 + 2×1 + 3×20 + 4×8 = 13 + 2 + 60 + 32.
Swap Outer Pairs
Question 35. For 6-letter ABCDEF, swap A↔F and B↔E; keep C↔D. For SCHOOL:
a) L O O C S H
b) L O O H C S
c) L O O S C H
d) L O C O S H
Answer:
b) LOOHCS — S↔L, C↔O → L O O H C S.
Consonant +1, Vowel −1
Question 36. Apply to MANGO:
a) N Z O H N
b) N Z O H N (no spaces)
c) N Z N H N
d) N A O H P
Answer:
a) NZOHN — M(+1)=N, A(−1)=Z, N(+1)=O, G(+1)=H, O(−1)=N.
Reverse Triads
Question 37. Break into groups of 3 and reverse each: NOTEBOOK → NOT EBO OK → ?
a) TON OBE KO
b) TON OBE KO (no spaces)
c) TON EOB KO
d) TNO OEB OK
Answer:
a) TONOBEKO — NOT→TON, EBO→OBE, OK→KO.
Skip-1 Encode
Question 38. Write every second letter starting at 2nd, then append the remaining. For ELEPHANT:
a) L P A T E E H N
b) LPAT E EHN
c) L P A T E E H N (no spaces)
d) L P A T E E N H
Answer:
c) LPATEEHN — Even positions first: L,P,A,T; then odds: E,E,H,N → LPAT + EEHN.
Chain Substitution
Question 39. ‘Rain’→’Sun’, ‘Sun’→’Cloud’, ‘Cloud’→’Wind’. What gives shade?
a) Sun
b) Cloud
c) Wind
d) Rain
Answer:
b) Cloud — Shade is given by cloud in context; ‘Sun’ gives light, but chain target for shade is Cloud.
Left Rotate by 1
Question 40. Left-rotate letters by 1 (first goes last). For GARDEN:
a) ARDENG
b) ARDGEN
c) ARDEN G
d) ARDNEG
Answer:
a) ARDENG — G moves to end.
Right Rotate by 2
Question 41. Right-rotate by 2. For SCHOOL:
a) O L S C H O
b) O L S C O H
c) O L S H C O
d) O L S C H O (no spaces)
Answer:
d) OLSCHO — Last two (O L) to front.
Pair Sum to Letters
Question 42. Take pairs (A+B), (C+D) as sums (mod 26, 1–26 → A–Z). For LEMON:
a) Z T M (ignore middle)
b) Z T N
c) Z S N
d) Z T O
Answer:
a) ZTM — L(12)+N(14)=26→Z; E(5)+O(15)=20→T; middle M shown as M.
Center Expand
Question 43. For OCEAN, write from center outward: C E → then O A N:
a) C E O A N
b) E C O A N
c) E C A O N
d) C E A O N
Answer:
a) C E O A N — Middle two CE, then left O, then right A, then N.
Swap Even Positions
Question 44. For TIGERS (T I G E R S), swap positions 2 and 4, and 4 and 6 sequentially.
a) T E G I R S
b) T E G S R I
c) T I G S R E
d) T E G R I S
Answer:
b) TEGSRI — Step1: swap 2↔4 → T E G I R S; Step2: swap new 4↔6 → T E G S R I.
Vowel Cycle (A→E→I→O→U→A), Consonants same
Question 45. Apply to EDUCATION:
a) ID O C E T U A N
b) I D O C E T U A N
c) I D O C E T I A N
d) I D O C E T U A N (no spaces)
Answer:
d) IDOCETUAN — E→I, U→A? (Cycle U→A), A→E, I→O, O→U; consonants unchanged.
Very Tough Level Mental Ability Coding-Decoding for Class 5 (5 Questions)
Two-Step: Atbash then −1
Question 46. Mirror then −1. For PLANE:
a) J N Y L U
b) J N X L U
c) J O Y L U
d) K N Y L U
Answer:
a) JNYLU — Mirror: P→K, L→O, A→Z, N→M, E→V → KOZMV; −1 → J N Y L U.
Triple-Step: Reverse → Vowel+1 → Consonant−1
Question 47. Reverse → (vowel+1) → (consonant−1) on NOTE:
a) I S M U
b) H S M U
c) I R M U
d) I S L U
Answer:
a) ISMU — NOTE→ETON → vowels: E→I, O→U; consonants: T→S, N→M.
Index Math with Alternation
Question 48. For AB only: 1×pos(A) − 2×pos(B) = ?
a) −3
b) −2
c) −1
d) 0
Answer:
a) −3 — 1×1 − 2×2 = 1 − 4.
Blocks: (+1 on first half, −1 on second)
Question 49. For ELEPHANT, first 4 letters +1, last 4 letters −1:
a) FMFQ GZMS
b) FMFQ HZMS
c) FNFQ GZMS
d) FMFQ GAMS
Answer:
a) FMFQGZMS — ELEP→FMFQ; HANT→GZMS.
Alternating Atbash (odd only)
Question 50. Mirror odd positions, keep even same. For TIGER:
a) G I T E I
b) G I T E R
c) G H T E I
d) G I T D I
Answer:
a) G I T E I — T→G, I stays, G→T, E stays, R→I.
