In this segment of common sense reasoning, secret messages or words have to be decoded. They are coded as per a definite pattern/ rule which should be identified first. Then the same is applied to decode another coded word. This chapter makes you familiar with every type of problem based on coding-decoding.
Types of Coding-Decoding
Type 1: Letter Coding
In this type of question, the code of words is given in the form of letters of the alphabet.
Example 1. In a certain code, MEADOWS is written as RVNENFB. How will PRIESTS be written in that code?
Sol (1): As,
Example 2. ‘GANDHI WAS A GREAT LEADER OF INDIA’ is written as ‘RUFZOJ SUV U RDTUB QTUZTD EP JFZJU’ in the secret code language, then select the appropriate code from the given alternatives for each of the following words.
Sol: Here each letter of the original sentence is represented by a different code as shown below:
Hence the code for STRONG is VBDEFR and the code for ISLAND is JVQUFZ.
Example 3: The word RUN is coded as SVO. What should be the code letters of LAY?
Solution (1): MBZ
|R (+1) → S||L (+1) → M|
|U (+1) → V||A (+1) → B|
|N (+1) → O||Y (+1) → Z|
∴ LAY should be MBZ.
Example 4: In a certain code COURAGE is written as UOCREGA. How will JOURNAL be written in that code?
Solution (1): UOJRLAN
Clearly, when COURAGE is coded, some letters are interchanged with respect to their positions, i.e., odd position are interchanged.
Position of 1 changes to 3 and 3 to 1. Position of 5 changes to 7 and 7 to 5.
Hence, JOURNAL can be coded as UOJRLAN.
Type 2: Number Coding
In this type of coding, either alphabetical code values are assigned to the numbers or numerical code values are assigned to words.
Example 5: If D = 4 and COVER = 63, then BASIS = ?
Solution (1): 50
Clearly, in the given code, A = 1, B = 2, C = 3, ….. so that.
COVER = 3 + 15 + 22 + 5 + 18 = 63
∴ BASIS = 2 + 1 + 19 + 9 + 19 = 50.
Example 6: In a given code SISTER is coded as 535301. UNCLE as 84670 and BOY as 129. How is RUSTIC written in that code?
Solution (2): 185336
In this code, the alphabets are coded as follows:
|S I S T E R||U N C L E||B O Y|
|5 3 5 3 0 1||8 4 6 7 0||1 2 9|
If we apply this method, RUSTIC is coded as 185336.
Type 3: Substitution Coding
In substitution coding, some particular objects are assigned as code names and then a question is asked that is to be answered in the code language.
Example 7: If wall is called window, window is called door, door is called floor, floor is called roof and roof is called ventilator, what will a person stand on?
Solution: Since a person stands on the floor and in the given code language floor is called roof. Hence, roof will be the correct answer.
Type 4: Mixed Letter Coding
In this type of question, three or more sentences are given in the coded language and the code for a particular word is asked. To find the code for the particular word, pickup two sentences bearing a common word and the common code word will mean that word. Proceeding in a similar manner, we can be determined a particular code word for each word of given sentences.
Example 8: In a certain code language, ‘po ki top ma’ means ‘Usha is playing cards’. ‘kop ja ki ma’ means ‘Asha is playing tennis’, ‘ki top sop ho’ means ‘they are playing football’ and ‘po sur kop’ means ‘cards and tennis’. Which word in that language means ‘Asha’?
Solution. (1): In that language ‘ja’ means ‘Asha’
|po ki top ma||→||Usha is playing cards|
|kop ja ki ma||→||Asha is playing tennis|
|ki top sop ho||→||they are playing football|
|po sur kop||→||cards and tennis|
Comparing relation in each of the statements, we get Asha is coded as ‘ja’.
Type 5: Condition-based coding
In this type of coding-based question, a set of letters and their codes are given. After that, some conditions are given based on the combination of numbers/symbols. You have to solve the questions using these conditions.
Directions: Select the code of the given letter group in each question based on the following coding system and conditions.
- (i) If the first letter is a consonant and the last letter is a vowel, the codes for the first and last letters are to be interchanged.
- (ii) If the first and the last letter are vowels, both are to be coded as the code of the first letter.
- (iii) If both the first and last letters are consonants, both are to be coded as ‘δ’.
Example 9: Which combination correctly represents the letter group ‘IDZQGY’?
Solution (1): 6#[email protected]
Example 10: Which combination correctly represents the letter group ‘MZAEIK’?
Solution (3): δ2146δ
Condition (iii) is applied.
Example 11: Which combination correctly represents the letter group ‘GQEIFM’?
- none of these
Solution (4): δ546*δ
Condition (iii) is applied.
Example 12: Which combination correctly represents the letter group ‘UFEQYO’?
Solution (2): ©*457©
Condition (ii) is applied.
Example 13: Which combination correctly represents the letter group ‘NEMDYI’?
Solution (4): 643#78
Condition (i) is applied.
Type 6: Coded Letter of Word
These types of questions are based on code language which utilizes letters in the English alphabet.
Directions: In each question, there is a word written in capital letter, with one letter underlined. For each letter in that word, there is a code written in small letters. That code is denoted by 1, 2, 3, 4, and 5, not in the same order. You have to find out the exact code for the underlined letter in the word.
Example 14: QUITE
Solution. (4): Correct code for letter ‘Q’ is ‘pr’
Each letter in word QUITE is expressed as two letters, one behind and the other ahead of the given letter. Therefore, ‘A’ becomes ‘zb’, ‘B’ comes ‘ac’, and so on.
Example 15: PRISM
Solution. (4): Correct code for letter ‘R’ is ‘Q’
Each letter in the word PRISM is coded as one letter behind. Therefore, ‘A’ becomes ‘z’, ‘B’ comes ‘a’, and so on.
Example 16: BEAST
Each letter in the word BEAST is coded as three letters ahead. Therefore, ‘A’ becomes ‘d’, ‘B’ comes ‘e’, and so on.
Example 17: If EODGH is the code for BLADE, what is the code for CRICKET?
Solution (2): FULFNHW
Example 18: If EARTH is coded as 41590 and PALE as 2134, what is the code for PEARL?
Solution (4): 24153
codes for letters are: P=2, E=4, A=1, R=5 and L=3
Example 19: In a certain language, ‘put tir fin’ means ‘delicious juicy fruit’; ‘tie dip sig’ means ‘beautiful white lily’, and ‘sig lon fin’ means ‘lily and fruit’. What is the code for ‘and’?
Solution (1): ‘lon’
Common code from first and third statement for ‘fin’ is ‘fruit’. From second and third statement, ‘sig’ is ‘lily’. So ‘lon’ means ‘and’ in third statement.
Example 20: In a certain code, 15789 is written as XTZAL and 2346 is written as NPSU. How is 23549 written in the code?
Solution (2): NPTSL
∴ 23549 can be written in code as NPTSL.
Example 21: In a certain code DELHI is written as CDKGH. How is SUSPECT written in code?
Solution (2): RTRODBS
Clearly, we can see that each letter of the word DELHI is moved one step backward to obtain the code. Similarly, SUSPECT will be coded as RTRODBS.