Lets have a look at some of the selected mental ability coding-decoding questions with answers and practice for Class 6 with varied patterns – Caesar shifts, mirror (Atbash), alternating shifts, rotations, number mappings, block swaps, index-weighted sums, chain substitutions, and multi-step encodings. Click on the “Answer” to expand for the answer and short explaination.
Easy Level Mental Ability Coding-Decoding for Class 6 (15 Questions)
Letter Shift (+1)
Question 1. If CAT = DBU, then LION = ?
a) MJPO
b) MKQP
c) MJPN
d) MIQN
Answer:
a) MJPO — +1 each: L→M, I→J, O→P, N→O.
Direct Positions (A=1…Z=26)
Question 2. Code for TIGER as positions:
a) 20-9-7-5-18
b) 20-9-6-5-18
c) 19-9-7-5-18
d) 20-8-7-5-18
Answer:
a) 20-9-7-5-18.
Reverse Word
Question 3. If MARKET is written as TEKRAM, then GARDEN is:
a) NEDRAG
b) NEDGAR
c) NEDARG
d) DENGAR
Answer:
a) NEDRAG — Reverse the letters.
Atbash (Mirror A↔Z)
Question 4. Mirror of BOY is:
a) YLB
b) YLB (no spaces)
c) Y L B
d) ZKC
Answer:
b) YLB — B→Y, O→L, Y→B.
Sum of Positions
Question 5. If code(word) = sum of letter positions, code(BOOK) = ?
a) 40
b) 41
c) 43
d) 45
Answer:
c) 43 — 2+15+15+11.
Telephone Keypad
Question 6. Using ABC=2, DEF=3, GHI=4, JKL=5, MNO=6, PQRS=7, TUV=8, WXYZ=9, the code for HELLO is:
a) 43556
b) 443556
c) 435560
d) 43565
Answer:
a) 43556 — H4, E3, L5, L5, O6.
Word Substitution
Question 7. If ‘Pen’ is ‘Pencil’, ‘Pencil’ is ‘Marker’, and ‘Marker’ is ‘Brush’, what do we write with?
a) Brush
b) Pencil
c) Marker
d) Pen
Answer:
b) Pencil — We write with Pen, and ‘Pen’ is called ‘Pencil’.
Letter Shift (+2)
Question 8. If APPLE → CRRNG, then MANGO → ?
a) OCPIQ
b) OCPNQ
c) ODPJQ
d) NCPIQ
Answer:
a) OCPIQ — +2 each.
Extract Odd Positions
Question 9. Take letters at odd positions from NOTEBOOK.
a) NTEO
b) NTOB
c) NTEOK
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, E.
Reverse then +1
Question 11. Reverse the word and then shift each letter +1. For DOG:
a) H P E
b) E P H
c) H Q E
d) G O D
Answer:
a) H P E — DOG → GOD → HPE.
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 → YNN, then BEES → ?
a) ADDR
b) ADDS
c) ACDR
d) A DDR
Answer:
a) ADDR — −1 each.
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 — School→Library (first link).
Medium Level Mental Ability Coding-Decoding for Class 6 (15 Questions)
Letter Shift (+3)
Question 16. If BOY → ERB, then GIRL → ?
a) JLUO
b) JLVN
c) JKUO
d) JLTN
Answer:
a) JLUO — +3 each.
Atbash
Question 17. Mirror of MARKET is:
a) NZIVPG
b) NZIVKV
c) NAIVPG
d) MZIVPG
Answer:
a) NZIVPG — M→N, A→Z, R→I, K→P, E→V, T→G.
Alternate Shift (Odd +1, Even −1)
Question 18. Apply odd +1, even −1 to ORANGE.
a) PQB MFD
b) PQB MFE
c) PQB NFD
d) NQB MFD
Answer:
a) PQBMFD — 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).
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.
Reverse Middle (5-letter)
Question 21. Reverse only the middle 3 letters (BCD) of PLANT:
a) PALNT
b) PNLAT
c) P L A N T (no change)
d) PNALT
Answer:
a) PALNT — LAN → NAL.
Even Positions Extract
Question 22. Even-position letters of STRAWBERRY are:
a) TABRY
b) TRWER
c) TARBY
d) TARRY
Answer:
a) TABRY — positions 2,4,6,8,10.
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.
Consonant −1, Vowel +1
Question 24. Apply to NOTE:
a) MUSI
b) MTSF
c) NUSI
d) MURF
Answer:
a) 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 — 19+19.
Number-to-Letter
Question 26. 20-5-1-3-8 codes to:
a) TEACH
b) TOUCH
c) TEA CH
d) TEACHH
Answer:
a) TEACH.
Shift by Word Length
Question 27. Shift each letter by (word length). For MATH (length 4):
a) QEXL
b) QEXK
c) PEXL
d) QFYK
Answer:
a) QEXL — M→Q, A→E, T→X, H→L.
Digit Sum Code
Question 28. Sum positions; reduce to one digit. For SCHOOL:
a) 9
b) 8
c) 6
d) 7
Answer:
a) 9 — 72 → 7+2.
Triplet Product Small
Question 29. For ABC, code = A×B + C. For DOG:
a) 67
b) 60
c) 58
d) 43
Answer:
a) 67 — 4×15 + 7.
Left Rotate by 1
Question 30. Left-rotate letters by 1 (first goes last). For GARDEN:
a) ARDENG
b) ARDGEN
c) ARDNEG
d) AGDREN
Answer:
a) ARDENG.
Tough Level Mental Ability Coding-Decoding for Class 6 (15 Questions)
Caesar (+4)
Question 31. Shift +4 each. For PLANE:
a) TPERI
b) TPE RI
c) TQERI
d) TQFRI
Answer:
a) TPERI — P→T, L→P, A→E, N→R, E→I.
Alternate (+2, −1, +2, −1…)
Question 32. Apply on APPLES:
a) CORKGR
b) CORKGS
c) CNRKGR
d) CORKFR
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 — BAG → (Y Z T) → +1 → Z A U.
Index-Weighted Sum
Question 34. Value = Σ[i×pos(letter_i)]. For MATH:
a) 107
b) 114
c) 127
d) 95
Answer:
a) 107 — 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) LOOHCS
b) LOOHSC
c) L O O H C S
d) LCOOHS
Answer:
a) LOOHCS — S↔L, C↔O → L O O H C S.
Consonant +1, Vowel −1
Question 36. Apply to MANGO:
a) NZOHN
b) NBOHN
c) NAOHN
d) NZOIM
Answer:
a) NZOHN — M→N, A→Z, N→O, G→H, O→N.
Reverse Triads
Question 37. Break into groups of 3 and reverse each: NOTEBOOK → NOT EBO OK → ?
a) TONOBEKO
b) TONOEBKO
c) TNOOBEKO
d) TON EOB KO
Answer:
a) TONOBEKO — NOT→TON, EBO→OBE, OK→KO.
Chain Substitution
Question 38. ‘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; chain confirms the name mapping contextually.
Right Rotate by 2
Question 39. Right-rotate by 2. For SCHOOL:
a) OLSCHO
b) OSLCHO
c) OLSHCO
d) OLSOCH
Answer:
a) OLSCHO — last two OL to front.
Pair Sum to Letters
Question 40. Take pairs (A+B), (C+D) as sums (mod 26, 1–26 → A–Z). For LEMON (ignore middle M):
a) ZTM
b) ZTN
c) ZSM
d) ZTO
Answer:
a) ZTM — (L12+N14=26→Z), (E5+O15=20→T), middle shown M.
Center-Out Order
Question 41. For OCEAN, write from center outward: C E then O A then N.
a) CEOAN
b) CEONA
c) ECOAN
d) CEAON
Answer:
a) CEOAN.
Swap Even Positions Sequentially
Question 42. For TIGERS (T I G E R S), swap 2↔4, then 4↔6.
a) TEGSRI
b) TEGIRS
c) TIGSRE
d) TEGSIR
Answer:
a) TEGSRI — Step1: TEGIRS; Step2: swap positions 4 and 6 → TEGSRI.
Vowel Cycle (A→E→I→O→U→A; consonants same)
Question 43. Apply to EDUCATION:
a) IDOCETUAN
b) IDOCIT UAN
c) IDOCETUEN
d) IDUCETUAN
Answer:
a) IDOCETUAN — E→I, U→A, A→E, I→O, O→U; consonants unchanged.
Mirror at Odd, +1 at Even
Question 44. For TIGER, mirror odd positions and add +1 to even positions.
a) GJTFI
b) GHTFI
c) GJTEI
d) GITFI
Answer:
a) GJTFI — T→G, I→J, G→T, E→F, R→I.
Index Pair Math
Question 45. For AB only: 1×pos(A) − 2×pos(B) = ?
a) −3
b) −2
c) −1
d) 0
Answer:
a) −3 — 1×1 − 2×2.
Very Tough Level Mental Ability Coding-Decoding for Class 6 (5 Questions)
Two-Step: Atbash then −1
Question 46. Mirror then −1. For PLANE:
a) JNYLU
b) JNXLU
c) KNYLU
d) JNYLV
Answer:
a) JNYLU — PLANE → KOZMV → −1 → JNYLU.
Triple-Step: Reverse → (vowels +1) → (consonants −1)
Question 47. Apply to TIGER:
a) QIFOS
b) QHFOS
c) QIFNS
d) RIFOS
Answer:
a) QIFOS — Reverse: REGIT → vowels: E→I; consonants: R→Q, G→F, I→O, T→S.
Alternating Mirror (odd only)
Question 48. 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 same, G→T, E same, R→I.
Blocks: (+1 on first half, −1 on second)
Question 49. For ELEPHANT, first 4 letters +1, last 4 letters −1:
a) FMFQGZMS
b) FMFQHZMS
c) FNFQGZMS
d) FMFQGAMS
Answer:
a) FMFQGZMS — ELEP→FMFQ; HANT→GZMS.
Four-Step Hybrid
Question 50. Steps for word NOTE: (1) rotate right by 1, (2) Atbash, (3) shift +1, (4) take even positions only. What is the final string?
a) NH
b) ZV
c) AU
d) MV
Answer:
a) NH — NOTE → ENOT → Atbash: VMLG → +1: WNMH → even positions N,H.
