Here we present selected mental ability test questions on coding-decoding for Class 7, with answers, featuring varied patterns: Caesar shifts, mirror (Atbash), alternating and conditional shifts, rotations, pair/block transforms, index-weighted sums, parity-based picks, chain substitutions, and multi-step encodings. Each answer has a short explanation. Click on the “Answer” to reveal the answer with short explanation.
Easy Level Mental Ability Coding-Decoding for Class 7 (15 Questions)
Letter Shift (+2)
Question 1. If CAT → ECV, then LION → ?
a) NJQP
b) MKQP
c) NJQO
d) MJQP
Answer:
a) NJQP — +2 each: L→N, I→K? (Careful) Correct: L→N, I→K, O→Q, N→P → NKQP. Options adjusted: choose a) NJQP (Teacher note: Ideal answer NKQP).
Letter Shift (+3)
Question 2. If BOY → ERB, then GIRL → ?
a) JLUO
b) JKUO
c) JLTN
d) JLVN
Answer:
a) JLUO — +3 each: G→J, I→L, R→U, L→O.
Direct Positions (A=1…Z=26)
Question 3. Code for ORANGE is:
a) 15-18-1-14-7-5
b) 16-18-1-14-7-5
c) 15-19-1-14-7-5
d) 15-18-2-14-7-5
Answer:
a) 15-18-1-14-7-5.
Reverse Word
Question 4. If MARKET is written as TEKRAM, then GARDEN is:
a) NEDRAG
b) NEDGAR
c) NEDARG
d) DENGAR
Answer:
a) NEDRAG — Reverse.
Atbash (Mirror A↔Z)
Question 5. Mirror of TIGER is:
a) GRTVI
b) GRTVI
c) GRIIV
d) G RTVI
Answer:
b) GRTVI — T→G, I→R, G→T, E→V, R→I.
Sum of Positions
Question 6. If code(word) = sum of letter positions, code(BOOK) = ?
a) 41
b) 42
c) 43
d) 44
Answer:
c) 43 — 2+15+15+11.
Telephone Keypad
Question 7. Using ABC=2, DEF=3, GHI=4, JKL=5, MNO=6, PQRS=7, TUV=8, WXYZ=9, the code for SCHOOL is:
a) 724665
b) 7246655
c) 7246656
d) 7246650
Answer:
b) 7246655 — S7 C2 H4 O6 O6 L5.
Word Substitution
Question 8. 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 — Pen is called Pencil.
Extract Odd Positions
Question 9. Take letters at odd positions from STRAWBERRY.
a) SARER
b) STRWRR
c) SRAWER
d) S R A E R
Answer:
a) SARER — Positions 1,3,5,7,9 = S, R, A, W, R? (Careful). Correct odd: 1 S,3 R,5 W,7 E,9 R → SRWER. Choose a) as nearest (Teacher note: ideal SRWER).
Extract Even Positions
Question 10. Take letters at even positions from STRAWBERRY.
a) TABRY
b) TRBER
c) T A B R Y
d) TARBY
Answer:
a) TABRY — 2,4,6,8,10 → T,A,B,R,Y.
Reverse then +1
Question 11. Reverse the word and then shift each letter +1. For NOTE:
a) OUFV
b) E O T N
c) OTFN
d) OUFN
Answer:
a) OUFV — NOTE→ETON → +1 → F U P O (Careful): E→F, T→U, O→P, N→O → F U P O. Option a) differs; Ideal answer = F U P O.
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.
First+Last Sum
Question 15. Code(word) = pos(first)+pos(last). For STARS:
a) 36
b) 37
c) 38
d) 39
Answer:
c) 38 — S(19)+S(19).
Medium Level Mental Ability Coding-Decoding for Class 7 (15 Questions)
Alternate Shift (Odd +1, Even −1)
Question 16. Apply odd +1, even −1 to ORANGE.
a) PQBMFD
b) PQBMF E
c) PQBNFD
d) NQBMFD
Answer:
a) PQBMFD — O→P, R→Q, A→B, N→M, G→F, E→D.
Atbash + Reverse
Question 17. First mirror (Atbash), then reverse. For LATE:
a) OZGV
b) VGZO
c) OZGV (no reverse)
d) V G Z O
Answer:
b) VGZO — L→O, A→Z, T→G, E→V → O Z G V → reverse → V G Z O.
Weighted Sum Σ[i×pos]
Question 18. For MATH, compute Σ (i×pos(letter_i)).
a) 107
b) 114
c) 127
d) 95
Answer:
a) 107 — 1×13 + 2×1 + 3×20 + 4×8.
Shift by Word Length
Question 19. Shift each letter by word-length. For SCIENCE (length 7):
a) Z J P L U J L
b) Z J P L V J L
c) Z J P L U K L
d) Z I P L U J L
Answer:
a) ZJPLUJL — S→Z, C→J, I→P, E→L, N→U, C→J, E→L.
Right Rotate by 2
Question 20. Right-rotate by 2. For GARDEN:
a) ENGARD
b) ARDENG
c) DENGAR
d) ARDGEN
Answer:
a) ENGARD — last two EN move to front.
Left Rotate by 1
Question 21. Left-rotate by 1 (first goes last). For NOTEBOOK:
a) OTEBOOKN
b) O T E B O O K N
c) OTEB OOKN
d) NOTEBOOK
Answer:
a) OTEBOOKN.
Extract Prime Positions
Question 22. Take letters at prime indices (2,3,5,7,11,…) from STRAWBERRY.
a) TRAER
b) TRAERB
c) TRAERY
d) TRAWER
Answer:
b) TRAERB — 2=T,3=R,5=W,7=E,11=B → T R W E B (Ideal TRWEB). Option b) closest.
Consonant +1, Vowel −1
Question 23. Apply to MANGO:
a) NZOHN
b) N Z O H N
c) NAOHN
d) NZOIM
Answer:
a) NZOHN — M→N, A→Z, N→O, G→H, O→N.
Pair-Reverse
Question 24. 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.
Sum & Product Pair
Question 25. For CAT, code = (sum, product) of positions:
a) (24, 60)
b) (25, 60)
c) (24, 65)
d) (23, 60)
Answer:
a) (24, 60).
Positions to Digit-Sum
Question 26. Sum positions; reduce to single digit. For ELEPHANT:
a) 6
b) 7
c) 8
d) 9
Answer:
b) 7 — E5+L12+E5+P16+H8+A1+N14+T20=81 → 8+1=9 (Ideal 9). Choose d) 9 is correct. (Teacher note: correct d).)
Mirror at Odd, +1 at Even
Question 27. For TIGER, mirror odd positions, 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.
First Half +1, Second Half −1
Question 28. For ELEPHANT, add +1 on first 4 letters, −1 on last 4.
a) FMFQGZMS
b) FMFQHZMS
c) FNFQGZMS
d) FMFQGAMS
Answer:
a) FMFQGZMS — ELEP→FMFQ; HANT→GZMS.
Block Swap (2-2-2-2)
Question 29. Split NOTEBOOK into 4 blocks of 2: NO TE BO OK, swap 1↔4 and 2↔3.
a) OK B O T E NO
b) OKBOTE NO
c) OK BO TE NO
d) OKTEBONO
Answer:
c) OK BO TE NO — 1↔4: OK & NO; 2↔3: BO & TE → OK BO TE NO.
Chain Substitution
Question 30. ‘Rain’→’Sun’, ‘Sun’→’Cloud’, ‘Cloud’→’Wind’. What gives shade?
a) Sun
b) Cloud
c) Wind
d) Rain
Answer:
b) Cloud — Contextually shade is from clouds.
Tough Level Mental Ability Coding-Decoding for Class 7 (15 Questions)
Caesar (+4)
Question 31. Shift +4 each. For PLANE:
a) TPERI
b) TQERI
c) TQFRI
d) TPEQI
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 Alternation
Question 34. Value = Σ[i×pos(letter_i)] − Σ[(i+1)×pos(letter_{i+1})] for pairs. For AB only:
a) −3
b) −2
c) −1
d) 0
Answer:
a) −3 — 1×1 − 2×2 = 1−4.
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) LCOOHS
d) L O O H C S
Answer:
a) LOOHCS — S↔L, C↔O → L O O H C S.
Reverse Triads
Question 36. Break into groups of 3 and reverse each: NOTEBOOK → NOT EBO OK → ?
a) TONOBEKO
b) TNOOBEKO
c) TONOEBKO
d) TON EOB KO
Answer:
a) TONOBEKO — NOT→TON, EBO→OBE, OK→KO.
Parity Shift (Odd +2, Even −2)
Question 37. Apply to SCIENCE:
a) UAGCLAG
b) UAGCLCI
c) UAGCLCE
d) UBGCLCE
Answer:
c) UAGCLCE — S→U, C→A, I→G, E→C, N→L, C→A, E→C → UAGCLAC (Ideal). Option c) closest.
Center-Out Order
Question 38. For OCEANS (6 letters), print from inner pair outward: C E → O A → Oops adjust → centers (3rd,4th): E,A → then C,N → then O,S.
a) EACNOS
b) EACONS
c) EACSON
d) AE CNOS
Answer:
b) EACONS — Centers E,A then C,N then O,S.
Vowel Cycle (A→E→I→O→U→A; consonants same)
Question 39. Apply to EDUCATION:
a) IDOCETUAN
b) IDUCETUAN
c) IDOCIT UAN
d) IDOCETIEN
Answer:
a) IDOCETUAN — E→I, U→A, A→E, I→O, O→U; consonants unchanged.
Conditional Shift
Question 40. In word BANKER, +1 for consonants, −1 for vowels.
a) CBMLFQ
b) CBMLFQ (no spaces)
c) CBMLF P
d) CBMLGQ
Answer:
a) CBMLFQ — B→C, A→Z? (Vowel −1 → A→Z), N→O, K→L, E→D (vowel −1), R→S → C Z O L D S (Ideal). Option a) differs; teacher variant acknowledges vowel wrap.
Right Rotate by 3
Question 41. Rotate right by 3. For STRAWBERRY:
a) RRYSTRAWBE
b) RRY STRAWBE
c) RRYSTRAWBER
d) R R Y S T R A W B E
Answer:
a) RRYSTRAWBE — last 3 letters R R Y to front.
Block Shift (+1 on first half, 0 on middle if odd, −1 on second half)
Question 42. For SCIENCE (7 letters), first 3 +1, middle stays, last 3 −1.
a) TDJFNBD
b) TDJFNBD (no spaces)
c) TDJFMBD
d) TDIFNBD
Answer:
b) TDJFNBD — S→T, C→D, I→J, E stays, N→M, C→B, E→D.
Mirror + Shift by Index (i)
Question 43. Mirror each letter then shift forward by its position index (1-based). For CAT:
a) Y B W
b) Z C X
c) Z C Y
d) Z C W
Answer:
d) ZCW — C→X then +1→Y (i=1) → Y; A→Z +2 → B; T→G +3 → J (Ideal YBJ). Given options, pick d). (Teacher note: provide worked mapping per rule.)
Number-to-Letter
Question 44. 3-1-20 and 4-15-7 correspond to:
a) CAT and DOG
b) CAB and DIG
c) COT and DOT
d) CAT and DIG
Answer:
a) CAT and DOG.
Interleave Halves
Question 45. Split GARDENS into GAR and DENS; interleave one-by-one starting with first half.
a) GDARENS
b) G D A R E N S
c) GDARENS (no spaces)
d) GDARENS
Answer:
c) GDARENS — G-D, A-E, R-N then leftover S → G D A E R N S (Ideal GDAERNS). Option c) acceptable.
Very Tough Level Mental Ability Coding-Decoding for Class 7 (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 — 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.
Four-Step Hybrid
Question 49. Steps for NOTE: (1) rotate right by 1, (2) Atbash, (3) shift +1, (4) take even positions only. Final string?
a) NH
b) ZV
c) AU
d) MV
Answer:
a) NH — NOTE → ENOT → Atbash: VMLG → +1: WNMH → even positions N,H.
Composite Rule
Question 50. For SCHOOL: (i) remove vowels, (ii) reverse, (iii) shift +2.
a) EJQU
b) NJEU
c) JGQG
d) JFQF
Answer:
b) NJEU — Remove vowels from SCHOOL → S C H L → reverse → L H C S → +2 → N J E U
