A code is 'arrangement of signs'. Accordingly, coding is a process for transmitting a message between the sender and the recipient without a third individual knowing it. The coding and decoding test is set up to judge the candidate's capacity to interpret the rule that codes a specific word/message and break the code to interpret the word.

Coding and decoding are divided into eight types. They are: 1. Letter coding 2. Direct letter coding 3. Number/Symbol coding 4. Matrix coding 5. Substitution coding 6. Deciphering message word coding 7. Deciphering number and symbol codes for messages 8. Jumbled coding 1. Letter coding: Here, in these questions, the letters in a word are replaced by certain different letters as indicated by a particular standard to frame its code. The candidate is required to detect the coding pattern/rule and answer the questions as needed. These questions are again divided into two cases. They are: 1. Coding: To form the code for another word: First word and its code is given and required to find the second word code following the same rule in first word and code. 2. Decoding: To find the word by analysing the given code: First word and its code is given and required to find the word if the code of second word is given following the same rule given in first word and code. 2. Direct letter coding: Letters were assigned codes as indicated by a set example or principle concerning the development or adjustment of letters and one needs to distinguish this hidden rule to decode a word. Some of the time, specific letters are made codes for specific letters without there being any set example. For example, consider a language in which A is coded as W, C as P, E as T, L as Z, S as B and T as K. Then, the code of CASTLE in that language is PWBKZT. Such kind of coding is known as direct-coding. In direct coding, the code letters occur in the same pattern as the corresponding letters occur in the words. In this type, in the questions either the specific codes of letters are given or the codes of two or more words are given and one is asked to calculate the codes from given words including just those letters for which the codes have already been mentioned. 3. Number/Symbol coding: In these questions, either numerical code values are assigned to a word or alphabetical code letters are assigned to the numbers. The candidate is required to analyse the code as per the questions. Letters and numbers are associated to each other in no other way with the exception of in connection to the position of the letters in the English letter set. Thus, it is possible that this connection holds or the coding must be done according to an arrangement of given rules. In all different cases, the question is one of direct-coding. This type is sub divided into two cases. They are: 1. When numerical/symbol codes are assigned to words. 2. When alphabetical codes are assigned to numbers. 4. Matrix coding:

• A word is represented by only one set of numbers as given in any one of the alternatives.
• The sets of the numbers given in the alternatives are represented by two case of alphabets as in the given matrices.
• The columns and rows of matrix I are numbered from 0 to 4 and those of matrix II from 5 to 9.
• A letter from these matrices can be represented first by its row and then the column number.
• Hence, need to identify the correct set for the word given in each question.

5. Substitution coding: Here, some specific words are assigned out certain substituted names. At that point a question is asked that is to be answers in the substituted code language. 6. Deciphering message word coding:

• Some messages are given in the coded language and the code for a specific word or message is inquired.
• To analyse such codes, any two messages bearing a typical word are gotten.
• The normal code-word will in this way speak to that word.
• Continuing likewise by grabbing every single combinations of two, the whole message can be decoded and the codes for individual words found.

7. Deciphering number and symbol codes for messages: A few gatherings of numbers/images, every coding a specific message , are given. Through an examination of the given coded messages, taking two at once, the candidate is required to find the number/image code for every word and after that detail the code for the given messages. 8. Jumbled coding: Deciphering individual letter codes by analysis: Certain sample words are given alongside their codes. The candidate is required to decode singular codes for various letters by contrasting, taking two words at once, and after that answer the given questions as needed.

Model 1:1. In a specific code, BEAT is composed as YVZG, then what will be the code of MILD? 2. If NARGRUED is coded as GRANDEUR, which word is coded as SERPEVRE ? Solution: Model 2: In a specific code, O is composed as E, A as C, M as I, S as O, N as P, E as M, I as A, P as N and C as S, then by what means will COMPANIES be composed in the code? Solution: Model 3: If P = 16, PAGE = 29, then what is PEN coded as? Solution: Model 4: If 'gold' is called 'diamond', 'diamond' is called 'gold', 'gold' is called 'silver' and 'silver' is called 'emarald', which is the cheapest jewel? Solution: Model 5: In a specific language, 'Sun shines brightly' is written as 'ba lo su', 'houses are brightly lit' as 'kado ula ari ba' and 'light comes from sun' as 'dopi kup lo nro'. What code word is written for 'sun' and 'brightly'? Solution: