How To Solve Coding and Decoding Questions for Bank Exams

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How to solve Coding and Decoding Questions for Bank Exams

How to solve Coding and Decoding questions for Bank Exams


Coding – Decoding is a way of transmitting a message between the sender and the receiver to prevent the important information from the unauthorized users. Data plays the most important part in any business operation and that’s why it needs to be protected from the third party.

In Coding-Decoding, the data is encrypted with the help of a common key by the sender and at the receiver side, encrypted data is decrypted in order to obtain original data by determining common key in encrypted data.

Coding and Decoding plays a vital role in the Reasoning Section of various competitive exams but the level of difficulty differs in them. For example, in SSC, the level of difficulty is easy to medium while in IBPS exams, the level of questions is difficult.

IMPORTANT POINTS TO REMEMBER: Coding and Decoding based pattern

  • Letter position (A=1, B=2, C=3, …… Y=25, Z=26)
  • Opposite position of letters (A=26, B=25 …… Z=1)
  • Sum 27 Rule:(Sum of the position of the 1st alphabet from the beginning and 1st alphabet from the last is always 27. Similarly, for 2nd from the beginning and 2nd from the last and so on. Eg: A+Z=27, B+Y=27, C+X=27).

Types of Coding-Decoding: – How to solve Coding and Decoding

  • Direct Letter Coding
  • Letter Coding
  • Number / Symbol Coding
  • Substitution
  • Decoding Message Word Codes

Direct Letter Coding:

This type of coding is also called direct-coding where the code letters occur in the same sequence as the corresponding letters.

Eg: In a certain code “TEACHER” is coded as “PLNQVLB”

Then how will “HEART” be coded?

Sol: Here code for ‘T’ will be ‘P’, ‘E’ will be ‘L’, ‘A’ will be ‘N’ and so on.

So, code for HEART = VLNBP

Letter Coding:

In Letter Coding, find out the relationship between the alphabets of the word with certain other alphabets according to a specific rule to form its code.

Eg: In a certain code “COMPUTER” is coded as “DPNQVUFS”

Then how will “TELEPHONE” be coded?

Sol: Each letter in the word “COMPUTER” is increased by one letter forward i.e, ‘C’ become ‘D’, ‘O’ become ‘P’ and so on.


Number / Symbol Coding:

In this type, either number or symbol is assigned to a word to form a code.

Eg: In a certain code “GAIN” is coded as 11

Then how will “LAP” be coded?

Sol: G=7    A=1    I=9    N=14

Rule: (Sum of consonants) – (Sum of vowels)

= (7+14) – (1+9)


So, LAP = (12+16) – 1 = 27


In this type, an object name is substituted with the different object name.

Eg: If “Red” is called “Green”

“Green” is called “Blue”

“Blue” is called “Sky”

“Sky” is called “Grey”

Then what is the color of the clear sky?

Sol: The color of the clear sky is “Blue” and as given, “Blue” is called “Sky”. So the color of clear sky is “sky”

Decoding Message Word Codes:

In this type, three or four complete phrases are given in the coded language and the code for a particular word is asked.

Eg: In a certain code language,

  1. ‘abbddf’ means ‘bring me water’;
  2. ‘tdkldf’ means ‘water is life’;
  3. ‘narckl’ means ‘life makes mischief’;
  4. ‘bdctkl’ means ‘life and bring’.

Which of the following means ‘mischief’ in the same code language?

Sol: As code of life=’kl’ (common in 2nd, 3rd& 4th code)

So, code for “mischief” will be either ‘na’ or ‘rc’.

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