Coding and Decoding

What is coding decoding ?

  • The code is the system of symbols, letters, or words given certain arbitrary meaning and is used for transferring messages which require secrecy or conciseness.

  • Coding is a method of transmitting messages between sender and receiver which is not understood by any third person.

  • Conspicuously, these codes contain various patterns, principles or arrangements which allow the receiver to crack the message or code at the other end using the similar pattern principles or arrangements involved.

Types of Coding Decoding Logic ?

  • Alphabet Coding

  • Number Coding

  • Mixed Coding

  • Coding by Subtitution

Alphabet Coding

  • In the letter or alphabet coding decoding questions, the person setting the code replace an alphabet by some other alphabets using a specific arrangement or pattern to form a code.

  • The other person has to decode the code using his mental and logical thinking ability.

  • Example : A B _ D


    Here the answer will be 'C' as it is written in alphabetical order.

Number Coding

  • In number coding decoding questions, the person setting the code allocates arithmetical code values to different words.

  • The other person has to decode the code using his mental and logically thinking ability

  • Example : If COLD is codded as 3782 then OLD will be coded as ?


    Ans : 782

  • Explanation : if we see COLD and it's code then we will get that C-3,O-7,L-8,D-2
    Now, for OLD the code will be - 782

Mixed Letter Coding

  • In mixed letter coding decoding questions, the person setting the code gives an entire message in the code language and asks the code of the particular word.

  • The other person has to pick the common word given in two different messages and then the common word picked will be checked with the code given.
  • Example :In a certain code, '253' means 'books are old'; '546' means 'man is old' and '378' means 'buy good books'. What stands for 'are' in that code?
    Ans : 2

    Explanation : In the first and second statements, the common code digit is '5' and the common word is 'old'.
    So, '5' means 'old'.
    In the first and third statements, the common code digit is '3' and the common word is 'book'.
    So, '3' means 'books'.
    Thus, in the first statement, '2' means 'are'.
Coding by Substitution

  • In substitution coding decoding questions, the person setting the code assigns some specific entities to code names and based on those entities the other person has to recognize the real code name.