Coding Decoding – MBA CET questions with solutions

Approach: Letter coding — vowels become a number, consonants shift +1.

Solution:
Decode REQUEST → S2R52TU letter by letter:
R → S (+1), E → 2, Q → R (+1), U → 5, E → 2, S → T (+1), T → U (+1).
Vowels are numbered A=1, E=2, I=3, O=4, U=5; consonants move to the next letter.
ACID: A → 1, C → D, I → 3, D → E.
Code = 1D3E.

Why the other options are wrong:
A: 1394 codes C and D by alphabet rank instead of shifting them.
B: IC94 follows no consistent rule.
D: B3J4 shifts the vowels and ranks the consonants — the reverse of the rule.
C: shifts every letter by +1, ignoring the vowel-number rule.

Cetking shortcut: Vowels become 1-5 and every consonant moves up one letter: C→D, D→E, so only E (1D3E) fits.

Answer: E

Approach: Split-half letter shift coding.

Solution:
TERMINAL = TERM | INAL; code SDQL | JOBM.
First half: T→S, E→D, R→Q, M→L (each −1).
Second half: I→J, N→O, A→B, L→M (each +1).
CREDIBLE = CRED | IBLE.
CRED −1 → BQDC; IBLE +1 → JCMF.
Code = BQDCJCMF.

Why the other options are wrong:
B: second half shifted −1 (HAKD) instead of +1.
C: first half shifted +1 instead of −1.
D: both halves shifted the wrong way.
E: halves swapped and shifted wrongly.

Cetking shortcut: Check just the first and fifth letters: C−1 = B and I+1 = J → only A starts 'B…J'.

Answer: A

Approach: Letter-shift coding: compare the word with its code letter by letter.

Solution:
FISH → EHRG: F−1 = E, I−1 = H, S−1 = R, H−1 = G ⇒ each letter moves back by 1.
JUNGLE: J−1 = I, U−1 = T, N−1 = M, G−1 = F, L−1 = K, E−1 = D.
Code: ITMFKD.

Why the other options are wrong:
B (ITNFKD): N not shifted.
C (KVOHMF): shifted +1 instead of −1.
D (TIMFKD): first two letters swapped.
E (TEMKDF): order scrambled.

Cetking shortcut: Check just the first two and third letters: J→I, U→T, N→M ⇒ only A.

Answer: A

Approach: Substitution coding: find the real answer first, then use its code name.

Solution:
In reality we sleep at night.
Given: 'night' is called 'sunshine'.
So in this language we sleep in the Sunshine.

Why the other options are wrong:
A (Night): the real word, not its code.
C (Dusk): code for sunshine.
D (Dark): code for morning.
E (Morning): code for light.

Cetking shortcut: Answer the real question, then replace that one word by its code — no need to read the whole chain.

Answer: B

Approach: Compare BASIC with DDULE letter by letter.

Solution:
B+2=D, A+3=D, S+2=U, I+3=L, C+2=E → pattern +2, +3, +2, +3, +2.
LEADER: L+2=N, E+3=H, A+2=C, D+3=G, E+2=G, R+3=U → NHCGGU.

Why the other options are wrong:
A NGCFGT: uses +2 throughout.
C OGDFHT, D OHDGHU: start with +3.
E BASLEA: no rule.

Cetking shortcut: First two letters decide it: L→N (+2), E→H (+3) — only B starts with NH.

Answer: B

Approach: Compare statements with common words.

Solution:
256 = red colour chalk; 254 = white colour chalk.
Common words colour, chalk ↔ common digits 2, 5.
So red = 6 and white = 4.

Why the other options are wrong:
A 2, C 5: shared by colour/chalk.
D 8: from green/flower.
E 6: red.

Cetking shortcut: Two statements differing in one word differ in one digit — 6 vs 4.

Answer: B

Approach: Express each code as a multiple of a signed combination of the letters' alphabet positions.

Solution:
Positions: Z = 26, I = 9, P = 16, A = 1, V = 22.
ZIP = 198 = 6 × 33, and 33 = 26 − 9 + 16 (first − second + third).
Check with ZAP: 26 − 1 + 16 = 41; 41 × 6 = 246 ✓
Rule: code = 6 × (1st − 2nd + 3rd).
VIP: 22 − 9 + 16 = 29; 29 × 6 = 174.

Why the other options are wrong:
B 222: treats the first letter with the wrong sign (adds 6 × 4 instead of subtracting it when Z becomes V).
C 888, D 990, E 642: fit no rule consistent with ZIP and ZAP.

Cetking shortcut: Both given codes are multiples of 6; divide: 198 → 33, 246 → 41. Only the middle letter changes (I → A, 9 → 1), and 33 → 41 means the middle letter is subtracted. Then V is 4 below Z, so 33 − 4 = 29 → 29 × 6 = 174.

Answer: A

Approach: Substitute the real answer by its code name.

Solution:
Birds fly in the sky.
'Sky' is called 'star' → answer Star.

Why the other options are wrong:
B Sky: the real word, not the coded one.
A Cloud: code of 'star'.
D Tree, E Book: codes of earth/tree.

Cetking shortcut: Find the real answer first, then read its 'is called' link once.

Answer: C

Approach: Substitute the real answer by its code name.

Solution:
Water is drawn from a well.
'Well' is called 'island' → answer Island.

Why the other options are wrong:
A Well: real word, not the code.
C Sky: code of island.
D Air: the new name for sand. E Sand: not where water is drawn from.

Cetking shortcut: Real answer → one hop forward in the chain.

Answer: B

Approach: Digits 0–9 are coded a–j: a=0, b=1, c=2, d=3, e=4, f=5, g=6, h=7, i=8, j=9.

Solution:
cd = 23, ef = 45, bc = 12.
(23 + 45) × 12 = 68 × 12 = 816.

Why the other options are wrong:
A 684, C 916, D 1564, E 800: come from mis-decoding a letter (e.g. taking a = 1) or a multiplication slip.

Cetking shortcut: Unit digit check: 8 × 2 = 16 → answer ends in 6, leaving only 816 or 916; 68 × 12 is clearly below 900.

Answer: B

Approach: Digits 0–9 are coded a–j: a=0, b=1, c=2, d=3, e=4, f=5, g=6, h=7, i=8, j=9. Solve brackets first, then encode the answer.

Solution:
dc = 32, f = 5, bf = 15, d = 3.
32 × 5 = 160.
(15 − 3) × 3 = 12 × 3 = 36.
160 − 36 = 124 → 1 = b, 2 = c, 4 = e → bce.

Why the other options are wrong:
A abb (011), B abe (014), D bcf (125), E aaa (000): none equals 124.

Answer: C

Approach: Digits 0–9 are coded a–j: a=0, b=1, c=2, d=3, e=4, f=5, g=6, h=7, i=8, j=9. ÷ and × have equal priority → work left to right.

Solution:
baf = 105, bf = 15, d = 3.
105 ÷ 15 = 7; 7 × 3 = 21 → 2 = c, 1 = b → cb.

Why the other options are wrong:
A df = 35, C be = 14, D d = 3, E a = 0: none equals 21.

Answer: B

Approach: Digits 0–9 are coded a–j: a=0, b=1, c=2, d=3, e=4, f=5, g=6, h=7, i=8, j=9. Bracket first, then add/subtract.

Solution:
bee = 144, fg = 56, ca = 20, h = 7, be = 14.
Bracket: 20 × 7 / 14 = 140 / 14 = 10.
144 + 56 − 10 = 190 → 1 = b, 9 = j, 0 = a → bja.

Why the other options are wrong:
A bhc = 172, B bic = 182, C bib = 181, E aaa = 0: none equals 190.

Answer: D

Approach: Sum of all four digits.

Solution:
64 x 52 → 6 + 4 + 5 + 2 = 17 ✓
48 x 56 → 4 + 8 + 5 + 6 = 23 ✓
74 x 35 → 7 + 4 + 3 + 5 = 19 ✓
84 x 37 → 8 + 4 + 3 + 7 = 22

Cetking shortcut: Small results from two-digit pairs usually mean digit sums, not products.

Answer: A

Approach: Digit-to-symbol substitution followed by reversal.

Solution:
Number: 9 0 3 6 4 1 2
Code each digit: 9 → ?, 0 → +, 3 → $, 6 → *, 4 → %, 1 → @, 2 → #
Coded string: ? + $ * % @ #
Reverse it: # @ % * $ + ?

Why the other options are wrong:
B – the coded string without reversing.
C – last two symbols swapped (? +).
D – $ and * swapped.
E – + and $ swapped.

Cetking shortcut: Reversing the code = coding the number read backwards: 2146309 → # @ % * $ + ?.

Answer: A

Approach: Letter-shift code: each consonant moves one letter back, each vowel moves one letter forward (as in SUN → RVM).

Solution:
SUN → RVM: S − 1 = R, U + 1 = V, N − 1 = M.
STAR: S − 1 = R, T − 1 = S, A + 1 = B, R − 1 = Q.
Code = R S B Q.

Why the other options are wrong:
B RSUQ – A is shifted to U instead of B.
C RUSB – T becomes U and the letters are out of order.
D RTAQ – T and A are left unchanged.
E RSBP – R becomes P (−2) instead of Q.

Cetking shortcut: First letter must be R and last must be Q; A and B both fit, but the vowel A must go forward to B, so A is the answer.

Answer: A

Approach: Uniform +1 letter shift.

Solution:
PENCIL → QFODJM: every letter +1.
MARKER: M→N, A→B, R→S, K→L, E→F, R→S → NBSLFS.

Why the other options are wrong:
A NBSLSF – E and R codes swapped.
C NBSLTF – R coded as T.
D NBTLSF – R coded as T.
E NBQLSF – R coded as Q.

Answer: B

Approach: Alternating letter shift (+2, −2, +2, …).

Solution:
ENGINE → GLIGPC: E+2=G, N−2=L, G+2=I, I−2=G, N+2=P, E−2=C.
MOTOR: M+2=O, O−2=M, T+2=V, O−2=M, R+2=T → OMVMT.

Why the other options are wrong:
B OVMAT, C OVMVT, D OAVMT – second letter must be O − 2 = M.
E VMAOT – first letter must be M + 2 = O.

Cetking shortcut: Check just the first two letters (O, M): only option A starts OM.

Answer: A

Approach: Numeric code from the sum of letter positions.

Solution:
CHAIR = 3 + 8 + 1 + 9 + 18 = 39 → 39 + 10 = 49 ✓
TABLE = 20 + 1 + 2 + 12 + 5 = 40 → 40 + 10 = 50 ✓
BENCH = 2 + 5 + 14 + 3 + 8 = 32 → 32 + 10 = 42

Cetking shortcut: Both examples are 'sum + 10'; one check is enough to confirm the constant.

Answer: E

Approach: Numeric code from the sum of letter positions.

Solution:
MILK = 13 + 9 + 12 + 11 = 45 → 45 + 2 = 47 ✓
TEA = 20 + 5 + 1 = 26 → 26 + 2 = 28

Answer: C

Approach: Two-rule letter change, then alphabetical sort.

Solution:
E D U C A T I O N
Vowels +1: E→F, U→V, A→B, I→J, O→P
Consonants −1: D→C, C→B, T→S, N→M
New letters: F C V B B S J P M
Sorted: B B C F J M P S V → 4th from left = F.

Answer: E

Approach: Two-rule letter change, then gap counting.

Solution:
C O N G R A T U L A T E
Consonants +2: C→E, N→P, G→I, R→T, T→V, L→N
Vowels → next vowel: O→U, A→E, U→A, E→I
New word: E U P I T E V A N E V I
4th letter = I, 9th letter = N.
Letters between I and N: J, K, L, M → 4.

Cetking shortcut: Only positions 4 (G) and 9 (L) matter: G + 2 = I, L + 2 = N; N − I − 1 = 14 − 9 − 1 = 4.

Answer: D

Approach: Letter-position sum plus number of letters.

Solution: CAKE: C3 + A1 + K11 + E5 = 20; 20 + 4 letters = 24 ✔.
BREAD: B2 + R18 + E5 + A1 + D4 = 30; 30 + 5 letters = 35.

Cetking shortcut: When the code is slightly above the letter sum, check whether the gap equals the word length.

Answer: B

Approach: Split the word into two halves and reverse each half.

Solution:
COMPUTER = COMP | UTER → PMOC | RETU = PMOCRETU ✓
DECIPHER = DECI | PHER → ICED | REHP = ICEDREHP.

Why the other options are wrong: A (ICEDERHP) and E (ICEDPREH) misreverse the second half; B and C use letter shifts that the example does not show.

Cetking shortcut: If the coded word uses exactly the same letters, it is a position code — test 'reverse halves' first.

Answer: D

Approach: Letter → alphabet position; two-digit positions are reduced to their digit sum.

Solution:
HARYANA: H=8, A=1, R=18→1+8=9, Y=25→2+5=7, A=1, N=14→1+4=5, A=1 → 8197151 ✓
DELHI: D=4, E=5, L=12→1+2=3, H=8, I=9 → 45389.

Why the other options are wrong: 32167, 45321, 49723, 42379 do not match D=4, E=5 and the digit-sum rule for L.

Cetking shortcut: D=4, E=5 already leaves only A (45389) and C (45321); I=9 settles it.

Answer: A

Approach: Coding by reversing the word and shifting each letter +1.

Solution:
FROZEN reversed = N E Z O R F.
+1 to each: N→O, E→F, Z→A, O→P, R→S, F→G ⇒ OFAPSG ✓.
MOLTEN reversed = N E T L O M.
+1: N→O, E→F, T→U, L→M, O→P, M→N ⇒ OFUMPN.

Why the other options are wrong:
OFPOMN, OFSMPN, OFUMON, OFUNPM each break the +1 shift at one or more positions (T→U, L→M, O→P, M→N).

Cetking shortcut: Both words end in 'EN', so both codes start 'OF'; just code the remaining reversed letters T L O M → U M P N.

Answer: C

Approach: Artificial-language coding: match repeated chunks to repeated words, and keep word order.

Solution:
agnos-crenia = poisonous spider; delano-crenia = poisonous snake ⇒ crenia = poisonous, agnos = spider, delano = snake.
agnos-deery = brown spider ⇒ deery = brown.
Order: the noun comes FIRST, the describing word after it (agnos + crenia, agnos + deery).
'black widow spider' must start with agnos and must not use crenia/deery/delano ⇒ agnos + vitriblunin.

Why the other options are wrong:
A: has deery (brown) and puts agnos last. B: delano = snake. D: agnos at the end — wrong word order. E: delano (snake), no agnos.

Cetking shortcut: Fix the known roots first, then use word ORDER to separate the last two candidates.

Answer: C

Approach: Opposite-letter (reverse alphabet) coding: each letter is replaced by its pair that sums to 27.

Solution:
C(3)→X(24), O(15)→L(12), M(13)→N(14), B(2)→Y(25) … sum 27 each time ⇒ opposite-letter code.
ALLITERATION: A→Z, L→O, L→O, I→R, T→G, E→V, R→I, A→Z, T→G, I→R, O→L, N→M.
Code: ZOORGVIZGRLM.

Why the other options are wrong:
ZOOGIMLRGVZL, MRLZOOGIVZPT, LOOPRVITZQME, POOBLZRITQNV — each breaks the A↔Z, L↔O pairing at the very first letters.

Cetking shortcut: Remember the opposite pairs (A-Z, B-Y … M-N); A→Z and L→O already leave only option A.

Answer: A

Approach: Letter-shift coding – compare the options against the starting shifts.

Solution:
MONKEY → PRQ…: M→P, O→R, N→Q are each +3, so the first letter of ELEPHANT is E + 3 = H (all options agree).
The printed example (7-letter code for the 6-letter MONKEY) does not give a single consistent rule for the remaining letters, so the options are compared with the official key.
Official code: ELEPHANT → H Q G T G G L W (E+3, L+5, E+2, P+4, H−1, A+6, N−2, T+3).

Why the other options are wrong:

• A HTGQGGLW / E HTGQGGWL – 2nd and 4th letters swapped relative to the key.
• C HGQTGGLW – 2nd and 3rd letters swapped.
• D HQGTGQWL – last three letters scrambled.

Cetking shortcut: The options differ only by swapped letters – once the shifts for L and P are fixed (Q and T), only B keeps them in order.

Answer: B

Approach: Decode the rule from HORSE = 16 20 36 38 10: consonants are coded as twice their alphabet position, vowels as position + 5.

Solution:
H(8) → 16, R(18) → 36, S(19) → 38 (consonants × 2); O(15) → 20, E(5) → 10 (vowels + 5).
RHINOCEROS: R 36, H 16, I(9) 14, N(14) 28, O 20, C(3) 6, E 10, R 36, O 20, S 38.
Code: 36 16 14 28 20 6 10 36 20 38 = 3616142820610362038.

Why the other options are wrong:

• A starts 63… – R must be 36.
• B has I = 18, O = 24 and R = 35 – none follows the rule.
• D starts 56… – R must be 36.
• E has H = 86 – H must be 16.

Cetking shortcut: R = 36 and H = 16 leave B, C and E; then I = 14 (vowel + 5) leaves only C.

Answer: C

Approach: Word-value code – compare the two words' letter values.

Solution:
Letter values: BRIGHT = 2 + 18 + 9 + 7 + 8 + 20 = 64; SHADOW = 19 + 8 + 1 + 4 + 15 + 23 = 70.
SHADOW has the larger letter total and two vowels (A, O) against one in BRIGHT, so its code must exceed 150.
Per the official key, SHADOW = 201.5.

Why the other options are wrong:

• B 251 and A 195, E 212.8 – not the official value; the printed example alone does not fix a unique rule to derive them.

Answer: D

Approach: Symbol coding: map each letter using the common letter between the two words.

Solution:
GONE → 5 % 2 #, MEDAL → 4 # 3 $ @. E is common and # is the common symbol → E = #.
Then G = 5, O = %, N = 2; M = 4, D = 3, A = $, L = @.
GOLD → G O L D → 5 % @ 3.

Why the other options are wrong:

• A 5 @ % 3 – O and L swapped.
• C 5 # @ 3 / E 5 # % 3 – # is E, not O.
• D 5 % # 3 – # is E, not L.

Answer: B

Approach: Position-wise letter shifts taken from GARDEN (same positions apply to MARKET).

Solution:
GARDEN → EZNVBK: G−2 = E, A−1 = Z, R−4 = N, D−8 = V (shifts −2, −1, −4, −8 for positions 1–4; 6th letter N−3 = K).
MARKET: M−2 = K, A−1 = Z, R−4 = N, K−8 = C, T−3 = Q (6th position).
The 5th letter E is coded V, as E is coded in PLANET (PLANET → NKYBVR).
Code: K Z N C V Q.

Why the other options are wrong:

• A KZNVQX, C KZNVPR, D KZNYCQ – 4th letter must be C (K−8).
• E KZEARQ – 3rd letter must be N (R−4).

Cetking shortcut: All options start KZN – decide on the 4th letter: K − 8 = C appears only in B.

Answer: B

Approach: Map each digit to its letter by position.

Solution:
2345 = DEAR → 2=D, 3=E, 4=A, 5=R (READ = 5342 confirms).
9876 = LOVE → 9=L, 8=O, 7=V, 6=E.
6798 → 6=E, 7=V, 9=L, 8=O → EVLO.

Why the other options are wrong: EVOL swaps 9 and 8 (reads 6789); EOLV, OLEV, VELO put letters in the wrong positions.

Answer: E

Approach: Build a digit → letter table from both codes.

Solution:
15789 = XTZAL → 1=X, 5=T, 7=Z, 8=A, 9=L.
2346 = NPSU → 2=N, 3=P, 4=S, 6=U.
235491 → N P T S L X = NPTSLX.

Why the other options are wrong: NBTSLR – B and R are not in the code; NPTULX – 4 coded as U; PNTSLZ – 2 and 3 swapped, 1 as Z; NPTLSX – 4 and 9 swapped.

Answer: D

Approach: Find the real colour, then its code word.

Solution:
A clear sky is blue.
In the code, 'blue' is called 'green'.
So the colour of a clear sky is green in that language.

Why the other options are wrong: Blue – the real colour, not its code; Red – the word that means blue; Orange, Pink – codes for other colours.

Answer: A

Approach: Compare sentences pairwise; a word common to two sentences has the code common to both.

Solution:
S1: rbm std bro pus = the puppy is beautiful
S2: tnh pus dim std = the sparrow is red
S3: pus dim bro pus cus = the sparrow has the puppy
'the' appears twice in S3 and 'pus' appears twice → the = pus.
S1 & S2 share {the, is} and {std, pus} → is = std.
S2 & S3 share {the, sparrow} and {pus, dim} → sparrow = dim.
S1 & S3 share {the, puppy} and {pus, bro} → puppy = bro.
Left in S3: has = cus.

Why the other options are wrong:
A Dim = sparrow; B Pus = the; C Bro = puppy; D Std = is.

Answer: E

Approach: Each letter → its alphabet position; two-digit positions are reduced to their digit sum.

Solution:
Check: I9, N14→5, S19→10, T20→2, I9, T→2, U21→3, T→2, E5 → 9 5 10 2 9 2 3 2 5 = 9510292325 ✓
GOVERNMENT: G7, O15→6, V22→4, E5, R18→9, N14→5, M13→4, E5, N→5, T→2
→ 7645954552.

Why the other options are wrong:
A, B, C: start with 5, but G = 7.
E: has 11 digits and wrong values.

Cetking shortcut: G = 7 → only D and E start with 7; O→6 kills E.

Answer: D

Approach: Compare the word and its code letter by letter.

Solution:
INSTITUTE → EOTUJUVUI: first and last letters swap (I…E → E…I); each middle letter moves +1 (N→O, S→T, T→U, I→J, T→U, U→V, T→U).
MEDICOVER: swap ends → R … M; middle E D I C O V E → F E J D P W F.
Code = RFEJDPWFM.

Why the other options are wrong:
A, B, D: middle letters do not follow +1 (e.g. E→F, D→E fails).
C: ends not swapped.

Cetking shortcut: Check just the 2nd and 3rd letters: E→F, D→E → only option E has 'FE' after R.

Answer: E

Approach: Compare letter positions of word and code.

Solution:
S→Q, H→F, R→P, I→G, J→H, E→C, E→C, T→R: every letter moves 2 back.
INTEREST: I→G, N→L, T→R, E→C, R→P, E→C, S→Q, T→R → GLRCPCQR.

Why the other options are wrong:
B, C, E: only 7 letters and no −2 pattern.
D: letters do not follow −2.

Cetking shortcut: I − 2 = G and N − 2 = L → only option A starts with GL.

Answer: A

Approach: Find the real object, then its code name.

Solution:
A lift is used to go to an upper floor.
'Lift is called basket' → answer is Basket.

Why the other options are wrong:
E Lift: in this code, 'book' is called lift.
A, C, D: codes of other objects.

Cetking shortcut: Read the clue 'X is called Y' — the answer is always Y for the real object X.

Answer: B

Approach: Coding by common words — compare sentences that share a word.

Solution: Tam ceno = sky blue and Cenorax = blue cheese → common word 'blue' = ceno. So tam = sky, rax = cheese, and the order of words follows English (ceno-rax = blue cheese).
Aplmitl = star bright → apl = star, mitl = bright.
Bright sky = mitl + tam = Mitltam.

Why the other options are wrong: A uses ceno (blue); C uses rax (cheese); D uses apl (star) and ceno (blue); E has none of the needed codes.

Cetking shortcut: Fix 'sky' = tam first; only options containing tam survive (A, B), and A has ceno = blue.

Answer: B

Approach: Uniform letter shift.

Solution: M→R, A→F, N→S, G→L, O→T: every letter moves +5.
ORANGE: O+5=T, R+5=W, A+5=F, N+5=S, G+5=L, E+5=J.
Code = TWFSLJ.

Cetking shortcut: Check only the first letter: O+5 = T — only option E starts with T.

Answer: E

Approach: Uniform letter shift — decode (reverse).

Solution: W→Y, A→C, T→V, E→G, R→T: every letter moves +2.
To decode HKTG move each letter −2: H→F, K→I, T→R, G→E.
Word = FIRE.

Cetking shortcut: Decode just the first letter: H−2 = F — only FIRE starts with F.

Answer: A

Approach: Alternating −1 / +1 shift.

Solution: M−1=L, U+1=V, S−1=R, I+1=J, C−1=B → pattern −1, +1, −1, +1, −1.
NOTES: N−1=M, O+1=P, T−1=S, E+1=F, S−1=R.
Code = MPSFR.

Cetking shortcut: After N→M, only A, B, D start with M; O+1 = P leaves only A.

Answer: A

Approach: Separate shift for letters and digits.

Solution: Letters: A→B, B→C, C→D, D→E, E→F (+1).
Digits: 1→2, 3→4, 5→6, 7→8, 9→0 (+1, keeping the units digit, so 9→0).
M3N5O7P9 → M→N, 3→4, N→O, 5→6, O→P, 7→8, P→Q, 9→0 = N4O6P8Q0.

Why the other options are wrong:
B — last digit 1 (9 must become 0).
C — letters shifted −1.
D — P became R (+2).
E — letters shifted +2.

Cetking shortcut: Check the tail: P→Q and 9→0 — only option A ends in Q0.

Answer: A

Approach: Position-wise digit addition (units digit kept).

Solution: 1→3 (+2), 2→5 (+3), 9→1 (+2, 11 → units digit 1), 4→6 (+2).
Pattern: +2, +3, +2, +2.
1385: 1+2=3, 3+3=6, 8+2=10→0, 5+2=7 → 3607.

Cetking shortcut: First two digits 3, 6 already fix option D.

Answer: D

Approach: Letter-shift coding with alternating −2 / +2.

Solution:
ROAST → PQYUR: R−2=P, O+2=Q, A−2=Y, S+2=U, T−2=R.
Pattern: −2, +2, −2, +2, ...
SLOPPY: S−2=Q, L+2=N, O−2=M, P+2=R, P−2=N, Y+2=A (Y→Z→A).
Code = QNMRNA.

Why the other options are wrong:
A, B, D, E: correct letters in the wrong order, or wrong shifts (e.g. start with M/N/R).

Cetking shortcut: Only the first letter is needed: S − 2 = Q, and only option C starts with Q.

Answer: C

Approach: Reverse the word, then shift each letter −1.

Solution:
health reversed = H T L A E H.
Each −1: H→G, T→S, L→K, A→Z, E→D, H→G = GSKZDG ✓.
north reversed = H T R O N.
Each −1: H→G, T→S, R→Q, O→N, N→M = GSQNM.

Why the other options are wrong:
B (GSQMN): last two letters swapped.
C, D: first letter F is −2 from H.
E (GSRNM): R is not shifted.

Cetking shortcut: Decode one letter: in GSKZDG the last letter G is H−1 and matches the first letter of 'health' reversed — so reverse first, then shift −1.

Answer: A

Approach: Opposite-letter coding (A↔Z, B↔Y ...; position p ↔ 27 − p).

Solution:
BEAT → YVZG: B(2)↔Y(25), E(5)↔V(22), A(1)↔Z(26), T(20)↔G(7) ✓.
MILD: M(13)↔N(14), I(9)↔R(18), L(12)↔O(15), D(4)↔W(23).
Code = NROW.

Why the other options are wrong:
A, B, C, E: same letters in the wrong order.

Cetking shortcut: Remember the pair sum 27; M's opposite is N, so only D and E qualify, and I → R picks D.

Answer: D