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Free Coding and Decoding MCQs with Answers

114 Coding and Decoding MCQs from Analytical and Logical Reasoning, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.

Coding and decoding questions replace letters, numbers, words or symbols with another pattern and ask you to identify the rule or decode a new item. Methods include alphabet positions, shifts, reversals, substitution, rearrangement, numerical values and separate rules for different parts of a code.

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114 questions · page 4 of 6

61. Each letter is replaced by the letter immediately before it in the alphabet, with A changing to Z. How is MATH coded?

Easy
  • A. LZSG
  • B. NZUI
  • C. LZUH
  • D. KZSG

Explanation: Move each letter back by one place: M becomes L, A becomes Z, T becomes S, and H becomes G. Therefore, MATH is coded as LZSG.

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Correct answer: LZSG

62. Letters in odd positions stay unchanged, while letters in even positions move one place backward in the alphabet. How is FISH coded?

Easy
  • A. FHSG
  • B. EHRF
  • C. FIGG
  • D. FISG

Explanation: F and S are in odd positions, so they stay unchanged. I moves to H and H moves to G, giving FHSG.

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Correct answer: FHSG

63. The first letter is moved forward by 1 place, the second by 2 places, the third by 3 places, and so on. MATE is coded as NCWI. How is MATE coded using this rule?

Fairly easy
  • A. NCWI
  • B. NBWH
  • C. ODXJ
  • D. MCVH

Explanation: M plus 1 is N, A plus 2 is C, T plus 3 is W, and E plus 4 is I. The result is NCWI.

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Correct answer: NCWI

64. The first letter is moved backward by 1 place, the second by 2 places, the third by 3 places, and so on. How is FISH coded?

Fairly easy
  • A. EGPD
  • B. EHRF
  • C. FHPE
  • D. DGOE

Explanation: F moves back 1 to E, I moves back 2 to G, S moves back 3 to P, and H moves back 4 to D. Thus, the code is EGPD.

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Correct answer: EGPD

65. Each letter is written as a two digit alphabet position, and the two digits are then reversed. For example, FISH becomes 60919080. How is CODE coded?

Moderate
  • A. 30514050
  • B. 03050415
  • C. 30510450
  • D. 30504150

Explanation: CODE has positions 03, 15, 04, and 05. Reversing each pair gives 30, 51, 40, and 50, so the code is 30514050.

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Correct answer: 30514050

66. Each letter is moved forward by a number of places equal to its own alphabet position, using alphabet wraparound. BAT becomes DBN. How is LAMP coded?

Moderate
  • A. XBZF
  • B. XBYF
  • C. WAZE
  • D. YCAH

Explanation: L moves forward 12 places to X, A moves forward 1 to B, M moves forward 13 to Z, and P moves forward 16 to F. Therefore, LAMP becomes XBZF.

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Correct answer: XBZF

67. First swap the letters in each adjacent pair, then move every resulting letter one place forward. For example, MATE becomes BNUF. How is FISH coded?

Hard
  • A. JGTI
  • B. JGSH
  • C. IFTI
  • D. KHUJ

Explanation: FISH becomes IFSH after swapping each pair. Moving every letter forward one place gives JGTI.

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Correct answer: JGTI

68. Add the word length to the alphabet position of every letter, using wraparound, and then reverse the result. LAMP becomes TQEP. How is TRAIN coded?

Very hard
  • A. SNFWY
  • B. SNGWY
  • C. YWFNS
  • D. SNFYW

Explanation: TRAIN has five letters, so add 5 to get Y, W, F, N, and S. Reversing these letters gives SNFWY.

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Correct answer: SNFWY

69. Multiply each letter's alphabet position by its position in the word, convert back to letters using wraparound, and then reverse the result. CODE becomes TLDC. How is MATE coded?

Very hard
  • A. THBM
  • B. TMHB
  • C. MBHT
  • D. UHBN

Explanation: MATE first becomes M, B, H, T because the products are 13, 2, 60, and 20. Reversing those letters gives THBM.

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Correct answer: THBM

70. Using A=1 through Z=26, replace each letter by the remainder when its position is divided by 3. Write a remainder of 0 as 3. How is BIRD coded?

Easy
  • A. 2331
  • B. 2321
  • C. 2231
  • D. 2332

Explanation: B is 2, I is 9 and gives 3, R is 18 and gives 3, and D is 4 and gives 1. Therefore, BIRD is coded as 2331.

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Correct answer: 2331

71. In this code, vowels stay unchanged. Each consonant is replaced by the next consonant in alphabetical order. How is FISH coded?

Fairly easy
  • A. GHSJ
  • B. GITK
  • C. FHTJ
  • D. GITJ

Explanation: F changes to G, I stays I, S changes to T, and H changes to J. Reading the results in order gives GITJ.

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Correct answer: GITJ

72. Divide the alphabet into groups of five: ABCDE, FGHIJ, KLMNO, and so on. Rotate each group one place to the left, while Z stays Z. For example, COLD becomes DKME. How is ZEBRA coded?

Moderate
  • A. ZACSB
  • B. ZBDSC
  • C. YACSB
  • D. ZABSC

Explanation: Within the groups, Z stays Z, E becomes A, B becomes C, R becomes S, and A becomes B. Thus ZEBRA becomes ZACSB.

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Correct answer: ZACSB

73. Write A=1 through Z=26 and divide the word into adjacent pairs. For each pair, write the absolute difference of the two values, followed by their sum, with no separators. MATE becomes 12141525. How is LION coded?

Hard
  • A. 321128
  • B. 322129
  • C. 321129
  • D. 312129

Explanation: L and I have difference 3 and sum 21, giving 321. O and N have difference 1 and sum 29, giving 129. Joining them produces 321129.

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Correct answer: 321129

74. To encode a word, first move its first letter forward by 1, its second by 2, its third by 3, and so on. Then arrange the resulting letters according to the original letters from highest to lowest alphabetically. MATE becomes WNIC. How is PLAN encoded?

Very hard
  • A. QNRD
  • B. RNQD
  • C. QRND
  • D. QDRN

Explanation: The shifting step changes PLAN to QNDR. The original letters in descending order are P, N, L, A, so their corresponding shifted letters…

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Correct answer: QRND

75. Which word cannot be made using only the letters of GARDEN?

Easy
  • A. ANGER
  • B. DANGER
  • C. GRADE
  • D. GREEN

Explanation: GARDEN contains only one E, while GREEN needs two Es. ANGER, DANGER and GRADE can each be formed from the available letters.

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Correct answer: GREEN

76. The letters RTEWA can be rearranged to form a word. Which category does that word belong to?

Easy
  • A. An animal
  • B. A liquid
  • C. A tool
  • D. Clothing

Explanation: RTEWA rearranges to WATER. Water is a liquid, not an animal, tool or item of clothing.

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Correct answer: A liquid

77. Which word cannot be made using only the letters of STREAM?

Fairly easy
  • A. MASTER
  • B. MATTER
  • C. SMART
  • D. STEAM

Explanation: MATTER requires two Ts, but STREAM contains only one T. MASTER, SMART and STEAM can all be formed from the given letters.

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Correct answer: MATTER

78. The letters LPEPA can be rearranged to form a word. Which category does that word belong to?

Fairly easy
  • A. A fruit
  • B. A vehicle
  • C. A profession
  • D. A building

Explanation: LPEPA rearranges to APPLE. An apple is a fruit, while the other choices are different categories.

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Correct answer: A fruit

79. Which word cannot be made using only the letters of RELATIONSHIP?

Moderate
  • A. PAINTER
  • B. PERSONAL
  • C. POSITION
  • D. RELATION

Explanation: POSITION needs two Os, but RELATIONSHIP has only one O. PAINTER, PERSONAL and RELATION use letters available in the longer word.

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Correct answer: POSITION

80. The letters RTOCDA can be rearranged to form a word. Which category does that word belong to?

Moderate
  • A. A vegetable
  • B. A vehicle
  • C. A profession
  • D. An instrument

Explanation: RTOCDA rearranges to DOCTOR. A doctor is a profession, not a vegetable, vehicle or instrument.

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Correct answer: A profession
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