Coding-Decoding Questions and Answers

Answer: A

47592 is written as 56683.

Compare 34687 with 43778 digit by digit:

3 + 1 = 4, 4 - 1 = 3, 6 + 1 = 7, 8 - 1 = 7, 7 + 1 = 8

The rule is +1, -1, +1, -1, +1. Applying it to 47592:

4 + 1 = 5, 7 - 1 = 6, 5 + 1 = 6, 9 - 1 = 8, 2 + 1 = 3, giving 56683.

The other options break the alternating pattern in one or more places, for example 55683 subtracts 2 from the second digit instead of 1.

Answer: C

'Goals' is written as 5 or 7.

Compare the coded sentences word by word. 'Many' appears in the first two sentences, and the only common code is 9, so many = 9. 'Scored' appears in the first and third, and the only common code is 3, so scored = 3.

That leaves the codes 5 and 7 for the remaining words of the first sentence, 'how' and 'goals'. Neither word appears anywhere else, so there is no way to tell which code belongs to which. 'Goals' is therefore 5 or 7, and the options giving 5 alone or 7 alone claim more than the information shows; 'None of these' is wrong because one of the two codes is correct.

Answer: C

CLOCK is spelt as CMNCL.

Compare WATCH with WBSCI letter by letter:

The pattern of shifts is 0, +1, -1, 0, +1. Applying it to CLOCK: C stays C, L becomes M, O becomes N, C stays C, K becomes L, giving CMNCL.

The other options break the pattern: CKPCJ reverses every shift, CKNCJ moves L and K backwards instead of forwards, and CMNDJ changes the fourth letter, which should stay C, and moves K backwards.

Answer: B

'White' is coded as 4.

'256' (red colour chalk) and '254' (white colour chalk) share 2 and 5, which stand for 'colour' and 'chalk'. The digit that differs, 4 in place of 6, must stand for the word that differs, 'white' in place of 'red'.

'589' also contains 5 with 'colour', confirming that 5 is 'colour' and 2 is 'chalk'. 8 belongs to 'green' or 'flower'.

Coding-decoding questions like this are solved by comparing codes that share words: common words map to common digits.

Answer: C

FAMILY is coded as GBNJMZ.

Compare MOTHER with NPUIFS: M becomes N, O becomes P, T becomes U, H becomes I, E becomes F and R becomes S. Every letter moves one place forward in the alphabet.

Applying the same rule: F to G, A to B, M to N, I to J, L to M, Y to Z, giving GBNJMZ.

GNBJZM jumbles the order, GBNZMZ codes I as Z, and EBNJMX moves F and Y backwards.

Answer: C

We would drink fire.

We drink water, and in this code 'water' is called 'fire'. So the answer is the code name for water, which is fire.

'Water' is the real name, not the code. 'Sky' is the code for air, and 'earth' is the code for fire, so neither stands for water.

Answer: D

The symbol for 'like' is ∞.

Compare the coded sentences. The first and third sentences share only the word 'I' and only the symbol Ͼ, so I = Ͼ. The second and third share 'you' and 'don't', and the symbols Ͽ and ϰ. The third sentence, 'I don't like you', has four symbols: Ͼ for I, Ͽ and ϰ for 'don't' and 'you', and so the remaining symbol, ∞, must be 'like'.

Ͼ is the code for 'I'. Ͽ and ϰ stand for 'you' and 'don't' in some order, so neither can be 'like'.

Answer: B

HIKM is written as 41.

The code is the sum of the alphabet positions of the letters:

\[ \begin{aligned} \text{ACEG} &= 1 + 3 + 5 + 7 = 16 \\ \text{DFGH} &= 4 + 6 + 7 + 8 = 25 \\ \text{HIKM} &= 8 + 9 + 11 + 13 = 41 \end{aligned} \]

36, 40 and 39 each come from miscounting one letter's position, for example taking K as 10 (40) or M as 11 (39).

Answer: B

DANCE = 27.

Each letter stands for its position in the alphabet: E = 5, and RED = 18 + 5 + 4 = 27. So

\[ \begin{aligned} DANCE &= 4 + 1 + 14 + 3 + 5 \\ &= 27 \end{aligned} \]

26 and 28 are one off, the result of mistaking the position of N or C, so 'None of these' is also wrong.

Answer: C

PREVIOUS is written QTHZJQXW.

In CUSTOMER → DWVXPOHV the letters move forward by 1, 2, 3, 4 and then repeat: C+1 = D, U+2 = W, S+3 = V, T+4 = X, O+1 = P, M+2 = O, E+3 = H, R+4 = V.

Applying the same shifts to PREVIOUS: P+1 = Q, R+2 = T, E+3 = H, V+4 = Z, I+1 = J, O+2 = Q, U+3 = X, S+4 = W, giving QTHZJQXW.

The other options start with O (a backward shift), have the wrong third letter (I) or contain nine letters.