Easy & Smart Way To Solve Coding-Decoding Question

easy & smart way to solve coding-decoding question

Solving coding-decoding question seems difficult to a lot if you can’t identify the logic behind it. ‘Coding-decoding’ questions are asked in reasoning ability section in Banking, SSC and many other competitive exams. Question from this chapter is not very difficult but requires a lot of practice to solve them in minimum time.

Here step-by-step we have discussed important ‘Coding-Decoding ’ concepts and smarter ways to solve ‘Coding-Decoding’ question.  You will easily manage your time and get a good score in the competitive exams like IBPS PO, SBI PO, IBPS RRB, IBPS Clerk, SBI Clerk, IBPS RRB, SSC CGL, SSC CGL, SSC MTS, NICL AO, LIC AAO, SBI Associate Clerk, SBI Associate PO  and others.

Please check out our previous topic on “Tips and tricks to solve ratio and proportion questions”

For easy understanding of this chapter, we have discussed a variety of ‘coding-decoding question’ from recent government job exam.

What is Coding-Decoding?

Coding is a process of representing a human-understandable data in such a way that it is hard to find the actual meaning. Coding is done before transmitting information in an encrypted form without it being known by any other person. The person who sends the code, is called the sender and the person who receives it, is called the receiver.

Before transmission, the data is encoded i.e, a certain set of rules are applied to the data and on receiving it, the same set of rules are applied to the data in reverse to obtain the original data, that is decoding.

Our area of studying “coding-decoding” is focused on the competitive exam like banking and SSC.

Coding can be of different types. there cannot be a particular rule applied to all. There are so many types of coding-decoding question, varies from simple to complex or easy to moderate.

Based on the previous occurrence of questions in reasoning section from coding-decoding we have categorized them in below.

  • Letter coding
  • Number coding
  • Substitution coding
  • Chinese coding/Numeral coding
  • Binary coding

Before we discuss each and every type, here are some points you need to memorize for solving problems in this topic

1.English alphabet position

english alphabet series2.Reverse position of the alphabet 

Position of a letter from the end=27- Position of a letter from the beginning

  1. Make a pair of opposite alphabet. E.g. az, by, cx, etcenglish alphabet with complementary position

General steps to solve ‘coding-decoding question’

  • Carefully observe alphabets or numbers given in the question.
  • Write down the respective position of the alphabet and try to find the sequence it follows whether it is ascending or descending.
  • Figure out the rule in which the words/alphabets/numbers follow.

Let us discuss each type of coding in detail

Letter coding

In this type of question, the letters of a word are replaced by certain other letters according to a specific pattern or rule to form a code. you need to figure out the coding pattern or rule to answer the question based on the pattern or rule.

For example,

E.g 1. If in a certain language. GAMBLE is coded as FBLCKF, how is FLOWER coded in that code?

Sol. In the first step compare the 1st letter of ‘GAMBLE’ with the 1st letter of ‘FBLCKF’. We find that G is replaced by F, which is the one position before G. Next letter A is converted to B, which is one position after A.

So, GAMBLE is coded as -1 and +1 alphabets in an alternative manner.

Now using the same logic we get code of FLOWER is EMNXDS.

E.g 2. If MEAT is written as TEAM, then BALE is written as-

Sol. if you observe carefully it is easily noticeable that ‘MEAT’ is coded by interchanging the position of the 1st and 4th letter, M and T. Position of the rest of the letters remain unchanged.

coding-decoding example solution

Now in the same way we get the code of ‘BALE’ is ‘EALB’.

E.g 3. In a certain code, BUILDER is written as JVCKSFE. How SEALING written in the same code?

Sol. If you observe carefully you will see that both the sequence and the position of the letter has been changed in the code.

solution for coding decoding

Applying the same rule we get the code of “SEALING” is “BFTKHOJ”

Number Coding

In this type of question, either numerical code value is assigned to a word or alphabetical code value assigned to the numbers.

E.g 4. If ‘Delhi’ is coded as ‘73541’ and ‘Calcutta’ as ‘82589662’, then how ‘Calicut’ can be written in that code language?

Sol. We have D-7, E-3 and so on

coding decoding soultionSimilarly, Calicut=8251896

E.g 5. If ‘ACNE’ is coded as 23, then ‘BOIL’ will be coded as?

Sol. In this question, it is clear that the code is formed by summing all the numerical position of the letters in the word ‘ACNE’. 


Code of ‘BOIL’=2+15+9+12=38

Substitution Coding

As the name suggests in this type of questions, some particular object or word is substituted with a different object or word. Then we follow the substitution and get the answer.

E.g 6. If cloud is called white, white is called rain, rain is called green, green is called air, air is called blue and blue is called water, where will the birds fly?

Sol. We know that birds fly in the ‘air’ and the ‘air’ is called blue. So the birds fly in the blue.

E.g 7. If the animals which can walk are called swimmers, animals who crawl are called flying, those living in water are called snakes and those which fly in the sky are called hunters. then what will a lizard be called?

Sol. We know that lizard is an animal which crawls. But in the given question the animal who crawls called flying. So lizard flying.

Chinese Coding/Numeral Coding

In this type of question, three to four messages are given in the coded language. The codes are not given in order and coded for a particular word or numeral is asked. To solve such question first you need to analyze the code. hence, any two messages bearing a common word/numeral are picked up. The common code represents that word present in both the message. Proceeding in a similar way by picking up all possible combinations of two. The whole message can be decoded. Individual code for the words can be found in the same way.

E.g 8. In a certain code language,

‘paint your house red’ is written as ‘ri fm ew cu’ 
‘gate of red colour’ is written as ‘lb ew op sa’ 
‘house of your choice’ is written as ‘sa cu ri nk’
‘gate with red paint’ is written as ‘gy op ew fm’

What is the code for ‘red’ in the given code language?

Sol. in the 1st and 2nd sentences the common word is ‘Red’ and the common code is ‘ew’.
So code for ‘Red’ is ‘ew’.

If the question is asked for the code of ‘house’ or ‘your’ or both, then the answer would be ‘can not be determined’ as they present only in two sentences which are not sufficient to answer. So, both words can be either ‘cu’ or ‘ri’.

Binary Coding

In this type of question, decimal numbers are coded by two symbols only. As binary number consists only ‘One’ and ‘Zero’. One symbol represents ‘Zero’ and other represents ‘One’.

E.g 9. in a certain code, Symbol for ‘0’ is @ and for ‘1’ is $. There are no other symbols for all other numbers greater than one. The numbers greater than one are to be written only by using the two symbols given above. The value of the symbol for 1 doubles itself every time it shifts from one place to the left.

a) What is the code of 13?

Sol. Binary of 13 is 8+4+0+1=1101. Therefore the code is $@$

b) Which decimal number is represented by $@@$?

Sol. If we replace the symbols with corresponding binary digit we get 1001, which represents decimal number 9. So the answer is 9.

Finally, we have reached the end of this topic. We have learned all the important tips and tricks to solve ‘coding-decoding’ question in your upcoming examination.

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