Reasoning Study Notes: Coding Decoding

Dear Readers,

Today we’ll discuss about Coding- Decoding. This topic is can fetch you marks easily but you need to know the right concepts and types of questions to practice.

In banking exams Coding Decoding questions can be asked in Data Sufficiency or there can be direct questions of coding-decoding itself. Usually 3-5 questions can be asked from this topic, thus it can fetch you easy marks with right practice.

Tips:

1. Try to focus on the thinking behind the solution.

Example 1: If GLORIOUS is coded as GOLRIOSU, code ‘JUDICIAL’?
Solution: This doesn’t need any explanation. A simple question based on observation.
As G L O R I O U S is coded as G O L R I O S U, we are that second and third letters are interchanged, again last two letters are also interchanged as shown below.
 
Using the same logic, the word J U D I C I A L is coded as J D U I C I L A

Example 2: If PEN is written as ‘+X’ and ENT is written as ‘X–’ in a certain code, how is TEN written in the same code?
Solution: The first thing to notice is that PEN has three characters while +X has only two. So two characters of PEN have been replaced by a single character. The same pattern can be seen in the case of ENT.
We must look for something common in the two of them PEN and ENT.
PEN = “+X”
ENT = “X–”
Common feature in both the above are EN & X.
So P = +, EN = X & T = –
TEN = –X

2. LETTER CODING:
Here letters are assigned codes according to a set pattern or rule concerning the movement or reordering / rearranging of letters and you need to detect this rule to decode a massage. Sometimes, specific codes are assigned to particular letters without any set pattern. Observe a few examples to know the various reordering or rearranging techniques.

Direction for example 3: In these questions the real alphabets in a word are replaced by certain other alphabets according to a specific rule to form its code.
Example 3: In a code language if TRAINS is coded as RTIASN, how PISTOL will be coded in the same language?
(a) SITLOP
(b) IPSTLO
(c) SIPTLO
(d) IPTSLO

Solution: If we compare the basic word {TRAINS} with the coded word {RTIASN}, we would see that the letters used in the word are same as in the basic word but their order of placement has been changed. Letter T at first position of the basic word has been placed at second position in the coded word and the letter R at the second position has been placed in the first position.
It means that in this question, letters of the basic word have been interchanged i.e. first letter with second, third with the fourth and so on. And thus we get the coded word. So PISTOL will be coded as IPTSLO. Hence option (d) is the answer.

3. NUMBER CODING:
Numerical code is given or value is assigned to a word. Here the only way to relate the alphabets & numbers is by associating the positions of the letters in the English alphabet. Sometimes any mathematical operation like addition or subtraction can be performed using the position of the letters. Direct coding questions can also be asked.

Direction for example 4: In this question, either numerical code values are assigned to a word or alphabetical code letters are assigned to the numbers.

Example 4: If PAINT is coded as 74128 and EXCEL is coded as 93596, then how would you encode ACCEPT?
(a) 455978
(b) 547978
(c) 554978
(d) 735961

Solution: In the given code the alphabets have been coded as follows:
P     A     I     N     T     E     X     C     L
7     4     1     2     8     9     3     5     6
So, in ACCEPT, A is coded as 4, C as 5, E as 9, P as 7 and T as 8. Hence the correct code is 455978 and therefore the answer is Choice (a).

4. MIXED LETTER/NUMBER CODING:
Some messages are given in the coded language and the code for a particular word or message is asked. To analyze such codes, any two messages bearing a common word are picked up. The common code number are picked up. Proceed in the similar fashion by picking up are possible combination of two, the entire message can be decoded.

Example 5: If ‘tee see pee’ means ‘drink fruit juice’; ‘see kee lee’ means ‘juice is sweet’ and ‘lee ree mee’ means ‘he is intelligent’, which word in that language means ‘swee’?
(a) see
(b) kee
(c) lee
(d) pee

Solution: In the first and second statement, the common word is ‘juice’ and the common code word is ‘see’. So, ‘see’ means ‘juice’.
In the second and third statements, the common word is ‘is’ and the common code is ‘lee’. So ‘lee’ means ‘is’. Thus in the second statement, the remaining word ‘sweet’ is coded as ‘kee’. Hence the answer is choice (b).

Example 6: In a certain code, ‘786’ means ‘study very hard’, ‘958’ means ‘hard work pays’ and ‘645’ means ‘study and work’. Which of the following is the code for ‘very’?
(a) 8
(b) 6
(c) 7
(d) Cannot be determined

Solution: Based on the same logic as used in the above question, the code for ‘very’ can be found out to be ‘7’, hence the answer is choice (c).

5. Coding decoding questions can also be asked in following types, these types were recently asked in SBI Exam and it puzzled many students. But if you read the instructions carefully and practice it, you can easily solve it.

Type: Symbols and Places of Digits

Example 6 : Triangle represents ∆ (1) and circle represents ○ (0). If triangle appears in unit's place then only its value is 0. If it appears in 10's place its value is 1 and when it appears in 100’s place is doubled to 2 like that it continues. Questions based on this
For example:
∆ ○ =0+0=0
∆○∆∆∆= 8+0+2+1+0=11

6.1. How will you represent ‘29’ in this code language?
(a) ∆∆∆○∆∆
(b) ○○∆∆∆○○
(c) ∆∆∆∆∆∆○
(d) ∆○∆○∆○∆
(e) ∆○∆∆○○ ○

Solution: (a)
∆∆∆○∆∆ = 16+8+4+0+1+0=29

6.2. What will be the code for  ○∆○∆○∆○ ?
(a) 12
(b)74
(c)21
(d)16
(e)4

Solution: (c)
○∆○∆○∆○ = 0+16+0+4+0+1+0=21

Type : (Tabular) Coding based on Conditions

Example 7: In each question below is given a group of numbers separated by comma (,). They are followed by four combinations of letters/symbols numbered (1), (2), (3) and (4). You have to find out which of the given combinations correctly represents the group of numbers based on the following coding system and mark the new code of that combination as the answer. If no condition is applicable coding will be according to the table.  If none of the four combinations correctly represents the group of numbers, mark ‘None of the above’, as the answer.

Conditions:
1) If the first number is a prime and the last number is a composite number then their codes are to be interchanged.
2) If both the first and the last number is Prime both are to be coded as $.
3) If both the first and the last letters are Composite and in between there are two or more Prime numbers then Prime numbers are to be coded as A.
4) If the first number is composite and the last number is a prime number, both are to be coded as the code for the composite number.

7.1.  4, 17, 88, 16, 3
(a) #,K,&,$,#
(b) A,K,&,$,#
(c) A,K,&,$,A
(d) $,K,&,$,$
(e) None of the above.

Solution: (a)
In 4,17,88,16,3 the first number is a composite and last is a prime; so codes will be according to condition (4).

7.2.  44, 11, 4, 2, 8
(a) $,S,#,C,$
(b) A, S,#,C,A
(c) B, S,#,C,@
(d) @,S,#,C,B
(e) None of the above

Solution: (d)
Given set of numbers are 44,11,4,2,8, here both first and last numbers are composite and there is only one prime number in between them. Hence no condition will apply and the codes are according to the given symbol table.