Coding Decoding: Reasoning Questions with Answers – Free Practice!

Coding Decoding Concepts

Q. 1 In a mystical land, a secret tribe communicates using a unique code. If DRAGON is coded as GUDJRQ. How will TIGER be coded in the same language?

Check Solution

Ans: B) WLJHU

Observe the pattern in coding:

D → G (+3), R → U (+3), A → D (+3), G → J (+3), O → R (+3), N → Q (+3).
Thus, each letter is shifted +3 positions forward in the alphabet.

T → W, I → L, G → J, E → H, R → U.

Q. 2 An old manuscript reveals a numerical code where SUGAR is written as 71913, and INDIA as 71871. Using the same code pattern, how would the word GRAIN be translated?

Check Solution

Ans: A) 93171

The code is derived from assigning specific numbers to letters:
S = 7, U = 1, G = 9, A = 1, R = 3.
Similarly, for INDIA:
I = 7, N = 1, D = 8, I = 7, A = 1.

Q. 3 A spy agency uses a special coding method for confidentiality. If the word MIRROR is written as 123343 and ERROR is written as 53343, how would they encode the word RIMMER?

Check Solution

Ans: B) 321435

From the given codes:
M = 1, I = 2, R = 3, O = 4. Also E = 5 from second code.
Thus, RIMMER = 321153.

Q. 4 In a magical puzzle book, words are reversed to create a code. For instance, APPLE becomes ELPPA, and TABLE becomes ELBAT. Using the same trick, how would the word CHAIR appear in this code?

Check Solution

Ans: B) RIAHC

The letters are reversed in order.
Thus, CHAIR becomes RIAHC.

Q. 5 In a certain language, BRIDGE is coded as TIRCVQ. How will BIRD be coded?

Check Solution

Ans: A) TRIC

Each letter is replaced as follows:

B → T, R → I, I → R, D → C, G → V, E → Q.
Similarly:

B → T, I → R, R → I, D → C

Q. 6 A puzzle club assigns unique codes to animals. For instance, DOG is represented as 415, and CAT as 312. What code would they assign to OAT?

Check Solution

Ans: A) 213

The code corresponds to the position of each letter in the alphabet:

D = 4, O = 1, G = 5 → DOG = 415.

C = 3, A = 1, T = 2 → CAT = 312.

That give, O = 1, A = 1, T = 2 → OAT = 112.

Q. 7 In a certain code, FISH is written as 7648, and BOAT is written as 4529. What is the code for SOFA?

Check Solution

Ans: a) 4572

From the given codes:
F = 7, I = 6, S = 4, H = 8, B = 4, O = 5, A = 2, T = 9.
For SOFA: S = 4, O = 5, F = 7, A = 2.

Q. 8 In an enchanted diary, words are turned into numbers. For example, CLOUD is written as 34521, and SPOUT as 67520. What number would represent COLD in this magical diary?

Check Solution

Ans: D) 3541

Mapping letters to numbers:
C = 3, L = 4, O = 5, U = 2, D = 1.
Thus, COLD = 3541.

Q. 9 A group of forest animals has invented their own secret language. In this code, LION is written as PLQO. Following the same rules, how would they encode the word BEAR?

Check Solution

Ans: D) FHCS

The coding rule shifts letters as follows:

L → P (+4), I → L (+3), O → Q (+2), N → O (+1).
Similarly:

B → F (+4), E → H (+3), A → C (+2), R → S (+1)

Q. 10 If ROTSF is coded as 619201518, then what will be ZOHAK coded as?

Check Solution

Ans: A

There are two operations here:
First: Every alphabet has been swapped around center position
Second: Output is then converted to it’s numerical value as per it’s position in alphabet series

Q. 11 In a certain language, vowels are replaced with the next consonant, consonants are replaced with the previous vowel (if any).

Example: “BAD” → B → previous vowel (A), A → next consonant (B), D → previous vowel (A) → “ABA”

What is the code for “RING”?

Check Solution

Ans: A)

R → previous vowel = O
I → next consonant = J
N → previous vowel = I
G → previous vowel = E
→ Code: OJIE

Q. 12 A word is coded by adding the position of a letter with its mirror in the word.

Example:

STOP
S(19) + P(16) = 35
T(20) + O(15) = 35
→ Code: [35, 35]

What is the code for WORD?

Check Solution

Ans: B)

W(23) + D(4) = 27
O(15) + R(18) = 33
→ Code = [27, 33]

Q. 13 If RDGSE is coded as SEHTF, then what will be QONUP coded as?

Check Solution

Ans: A)

Every alphabet is increased by 1

Q. 14 If LEVGE is coded as NGXIG, then what will be GQHET coded as?

Check Solution

Ans: D)

Every alphabet is increased by 2

Q. 15 If VVFTE is coded as ETFVV, then what will be PQOKM coded as?

Check Solution

Ans: A)

Alphabets have been swapped around centre position. So 1st letter is exchanged with 5th; and 2nd is exchanged with 4th letter

Q. 16 If KUIUP is coded as JTHVR, then what will be FQKUP coded as?

Check Solution

Ans: C)

First alphabet is changed by -1
Second alphabet is changed by -1
Third alphabet is changed by -1
Fourth alphabet is changed by 1
And fifth alphabet is changed by 2

Q. 17 If RKKKU is coded as TJKLS, then what will be PRPGJ coded as?

Check Solution

Ans: B)

First alphabet is changed by 2
Second alphabet is changed by -1
Third alphabet is changed by 0
Fourth alphabet is changed by 1
And fifth alphabet is changed by -2

Q. 18 If LONSL is coded as LOPTM, then what will be JKONL coded as?

Check Solution

Ans: A)

First alphabet is changed by 0
Second alphabet is changed by 0
Third alphabet is changed by 2
Fourth alphabet is changed by 1
And fifth alphabet is changed by 1

Q. 19 If JLWTD is coded as EUXMK, then what will be REKSQ coded as?

Check Solution

Ans: C)

Alphabets have been increased by 1 and then swapped around centre position.

Q. 20 If VDRDJ is coded as ICQCU, then what will be WHPUQ coded as?

Check Solution

Ans: B)

Alphabets have been decreased by 1 and then swapped around centre position.

Refer Important Aptitude Questions for Placement

Refer Questions for next topic: https://www.learntheta.com/aptitude-questions-data-sufficiency/