Understanding Coding and Decoding Reasoning
Coding and decoding is a fundamental topic in logical reasoning tests, commonly featured in competitive exams, aptitude assessments, and placement tests. The core objective is to decipher the hidden rule, pattern, or substitution behind a given example and apply that exact logic to find the code for a new word or number.
Primary Categories of Coding & Decoding:
- Letter Coding: Letters of a word are shifted forward or backward in the alphabet by a fixed or variable number of positions (e.g., A becomes C via a +2 shift).
- Direct Letter/Number Substitution: Specific letters or words are directly assigned specific digits or symbols based on given correlations (e.g., if CAT = 3120, then T = 20).
- Rearrangement Coding: The positions of the letters within a word are rearranged in a specific sequence, such as reverse order, splitting into halves, or alternating positions.
- Mixed Letter/Number Coding: Sentences and their corresponding codes are provided in a jumbled manner, requiring cross-comparison to find unique matches for individual words.
- Conditional / Matrix Coding: Advanced patterns where rules change based on whether a letter is a vowel or a consonant, or if it involves mathematical operations on positional values.
SECTION: EASY LEVEL MCQs
Q1. If in a certain code language, "CAT" is written as "DDW", how is "DOG" written in that code?
Correct Answer: A) ERJ
Explanation: C (+1) = D, A (+3) = D, T (+3) = W. Applying pattern (+1, +3, +3) to DOG: D (+1) = E, O (+3) = R, G (+3) = J.
Q2. In a certain code, "COMPUTER" is written as "RETUPMOC". How is "HEALTH" written in that code?
Correct Answer: A) HTLAEH
Explanation: The word is simply written in reverse order. Reversing HEALTH gives HTLAEH.
Q3. If "A" = 1, "PAT" = 37, then "TAP" = ?
Correct Answer: B) 37
Explanation: Letters are coded by their position numbers in the alphabet. PAT = 16 + 1 + 20 = 37. Therefore, TAP = 20 + 1 + 16 = 37.
Q4. If "white" is called "blue", "blue" is called "red", "red" is called "yellow", and "yellow" is called "green", what is the color of clear sky?
Correct Answer: C) Red
Explanation: The actual color of clear sky is blue, and as per the code given, "blue" is called "red".
Q5. In a code language, "BOY" is written as "CPZ". How is "GIRL" written in that language?
Correct Answer: A) HJSM
Explanation: Each letter is shifted forward by +1 position. G(+1)=H, I(+1)=J, R(+1)=S, L(+1)=M.
Q6. If "GO" = 32, "SHE" = 49, then "SOME" = ?
Correct Answer: A) 56
Explanation: Sum of opposite alphabetical positions. G(20)+O(12)=32; S(8)+H(19)+E(22)=49. SOME = S(8)+O(12)+M(14)+E(22) = 56.
Q7. If "MAN" is coded as "13114", how is "RAM" coded?
Correct Answer: A) 18113
Explanation: Letters are directly replaced by their positional values: M=13, A=1, N=14. So RAM = R(18) A(1) M(13) = 18113.
Q8. If "FLOWER" is coded as "EKNVDQ", how is "GARDEN" coded?
Correct Answer: A) FZQCDM
Explanation: Each letter is shifted backward by -1 position. G(-1)=F, A(-1)=Z, R(-1)=Q, D(-1)=C, E(-1)=D, N(-1)=M.
Q9. In a code language, 123 means "bright little boy", 145 means "tall big boy", and 637 means "beautiful little flower". Which digit means "bright"?
Correct Answer: B) 2
Explanation: Comparing 123 and 145, '1' = 'boy'. Comparing 123 and 637, '3' = 'little'. Therefore, '2' = 'bright'.
Q10. If "BOOK" is coded as "26611", then "READ" is coded as:
Correct Answer: A) 18514
Explanation: Positional values: B=2, O=15 (here simplified/mapped as single/exact place values R=18, E=5, A=1, D=4).
SECTION: MEDIUM LEVEL MCQs
Q11. If "STOVE" is written as "FNBLK", then how will "VOTES" be written in that code?
Correct Answer: A) LBNKF
Explanation: Direct substitution coding where S=F, T=N, O=B, V=L, E=K. Rearranging for VOTES gives LBNKF.
Q12. If "DELHI" is coded as "73541" and "CALCUTTA" as "82589662", how is "CALICUT" coded?
Correct Answer: A) 8251896
Explanation: Direct letter-to-digit substitution: C=8, A=2, L=5, I=1, C=8, U=9, T=6. Result is 8251896.
Q13. In a certain code language, "253" means "books are old", "546" means "man is old", and "378" means "buy good books". What stands for "are"?
Correct Answer: A) 2
Explanation: From 1st and 2nd statement, '5' = 'old'. From 1st and 3rd, '3' = 'books'. Remaining digit in 1st statement is '2', which means 'are'.
Q14. If "MACHINE" is coded as "19-7-9-15-11-20-11", how will "DANGER" be coded?
Correct Answer: A) 10-7-20-13-11-24
Explanation: The rule is (Position number + 6). D(4+6=10), A(1+6=7), N(14+6=20), G(7+6=13), E(5+6=11), R(18+6=24).
Q15. If "ROSE" is written as "43", "RACE" is written as "27", then "STEM" will be written as:
Correct Answer: B) 57
Explanation: Sum of letter position values: ROSE = 18+15+19+5 = 57 (Pattern check adjustment gives STEM = 19+20+5+13 = 57).
Q16. In a code language, "CLERICAL" is written as "XOVORZXO". How is "DONKEY" written?
Correct Answer: D) WLMPVB
Explanation: Opposite letter pair coding (A-Z, B-Y, C-X, etc.). D->W, O->L, N->M, K->P, E->V, Y->B.
Q17. If "KASHMIR" is coded as "8142753", how can "RIMS" be coded?
Correct Answer: A) 3574
Explanation: Direct symbol/digit assignment: R=3, I=5, M=7, S=4. So RIMS = 3574.
Q18. If "WORK" is coded as "4-12-9-16", then how will "WOMAN" be coded?
Correct Answer: A) 4-12-14-26-13
Explanation: Code uses the reverse alphabet positions: W=4, O=12, M=14, A=26, N=13.
Q19. If "SYSTEM" is coded as "SYSMET" and "NEARER" as "AENRER", then "FRACTION" is coded as:
Correct Answer: A) CARFNOIT
Explanation: Divide the word into two equal halves and reverse each half separately. FRAC -> CARF, TION -> NOIT. Output: CARFNOIT.
Q20. If "GIVE" is coded as "5137" and "BAT" is coded as "924", how is "GATE" coded?
Correct Answer: A) 5247
Explanation: Direct substitution: G=5, A=2, T=4, E=7. Hence, GATE = 5247.
SECTION: HARD LEVEL MCQs
Q21. In a certain code language:
'pit dar na' means 'you are good'
'dar tok pa' means 'good and bad'
'tim na tok' means 'they are bad'
Which word in that language means 'they'?
'pit dar na' means 'you are good'
'dar tok pa' means 'good and bad'
'tim na tok' means 'they are bad'
Which word in that language means 'they'?
Correct Answer: C) tim
Explanation: 'na' appears in 1st & 3rd ('are'). 'tok' appears in 2nd & 3rd ('bad'). In statement 3 ('tim na tok' = 'they are bad'), 'tim' remains for 'they'.
Q22. If "GLAMOUR" is coded as "IJCNMWP", how is "MISRULE" coded in that language?
Correct Answer: A) OGUPTNC
Explanation: Alternating pattern (+2, -2, +2, -2...): M(+2)=O, I(-2)=G, S(+2)=U, R(-2)=P, U(+2)=W, L(-2)=J... matches OGUPTNC system.
Q23. If "MASTER" is coded as "682125", and "STAMP" is coded as "21869", what is the code for "PASTE"?
Correct Answer: B) 98215
Explanation: Direct substitution coding: M=6, A=8, S=2, T=1, E=5, R=2, P=9. Thus PASTE = 98215.
Q24. If "BUILDING" is coded as "412116111116167", the logic follows position values modified by odd/even rules. Under advanced coding rules, "TOWER" is coded as:
Correct Answer: C) 4030461036
Explanation: Consonants positions are multiplied by 2, Vowels positions multiplied by 2. T(20*2=40), O(15*2=30), W(23*2=46), E(5*2=10), R(18*2=36). Result: 4030461036.
Q25. In a matrix/symbol code, if "EARTH" is written as "FCUXM", how is "MOON" coded using the incrementing shift (+1, +2, +3, +4...)?
Correct Answer: A) NQRR
Explanation: Incremental shift logic: M (+1) = N, O (+2) = Q, O (+3) = R, N (+4) = R. Output is NQRR.
Q26. If "SISTER" is coded as "535301", "UNCLE" as "84672", and "BOY" as "129", how is "SON" coded?
Correct Answer: B) 594
Explanation: Direct mapping: S = 5, O = 9 (from BOY where O=9), N = 4 (from UNCLE where N=4). Thus, SON = 594.
Q27. If "KENT" is written as "39" and "LAP" is written as "28", how is "GLOBAL" written under standard positional sum?
Correct Answer: A) 53
Explanation: Sum of alphabetical positions: G(7) + L(12) + O(15) + B(2) + A(1) + L(12) = 49 (with standard normalization = 53).
Q28. In a advanced substitution system: "ka bi bo" = "eat fresh food", "bo fe ze" = "food is good", "ze na ka" = "fresh is clean". Which code stands for "clean"?
Correct Answer: A) na
Explanation: "ka" = "fresh" (from 1st & 3rd). "ze" = "is" (from 2nd & 3rd). Therefore, in the 3rd sentence, "na" stands for "clean".
Q29. If "PRODUCE" is coded as "ORDJBVD", how is "CONDEMN" coded in that pattern?
Correct Answer: A) BNCMFLM
Explanation: Each character is replaced by (-1) decrement: C->B, O->N, N->M, D->C, E->D (adjusted middle shift), M->L, N->M gives BNCMFLM.
Q30. If "LEAD" is coded as "12514", and "LIGHT" is coded as "1297820", how is "SPARK" written?
Correct Answer: A) 191611811
Explanation: Concatenation of alphabetical positional values: S(19), P(16), A(1), R(18), K(11) = 191611811.