Ch.3 :- Coding Decoding : Introduction And formula


Coding Decoding verbal reasoning questions and answers for competitive exams and government jobs exam . It cover many of all india common mca and mba test.

The term Coding-Decoding primarily relates with message sent in secret form which cannot be understood by others easily. Coding, therefore, means rule or method used to hide the actual meaning of a word or group of words and decoding means themethod of making out the actual message that is disguised in a particular method of coding.In questions, a word (basic word) is coded in a particular way and candidates are asked to code other words in the same way. Questions of coding-decoding are designed to test candidate’s ability to understand the rule usedfor the coding and then translate it quickly to find out the coding for the given word. Types of these questions are manifold which initially pose a slight problem before the student as to how to solve the questions. It is therefore, required to discuss first the various probable types of questions which may be asked in the examination, before we switch over to the methods or steps used in solving these questions.

As a matter offact, there exists no uniform. and particular type or category of these questions according to which we could classify questions of coding-decoding. However, keeping in view the candidate’s convenience we have classified different types of questions with illustrations and explanations under different heads.

Category I
In this category of questions, a word is coded by simply changing the order of letters of the word.

Ex. 1. 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

Sol.: 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 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. In this code language word, PISTOL will be coded as IPTSLO. Hence, option Cd)is our answer.

Category II
In this category of questions, letters of a word are substituted for either a new letter or a numeric. And the same substitution helps to find out the coding of the word in questions. This substitution of letters may either be direct or in a jumbled up fashion. We shall discuss each type in detail in the following paragraphs.

(A) Direct Substitution
When letters of a word are substituted for the new letters and are placed in the coded word at the same position as in the basic word, then this method of substitution is called the direct substitution.

Ex. 2. In a code language if SUGARis coded as PKLTN and TEA is coded as QGT, how would you code GREAT in the same code language?

(a)ENGTP     (b)LNGTK   (c)LNGTQ     (d)LNGQT

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Here we see that S is substituted for P, U for K, G for L.A for T and R for N. And in the word TEA, T is substituted
for Q, E for G and A for T. Now we find that coding for letter A in SUGAR is T and coding for letter A in TEA is
also T. This implies that substitution of letter in coded word takes place in the same order as in basic word. In
simple words, in the word SUGAR letter S in the basic word has been substituted for a new letter and coded at
first place in the coded word, U at the second place, G at the third place and so on. Therefore, code for GREAT will be LNGTQ. Hence, option (c) will be the correct answer.

Ex. 3. In a code language if TEARS is coded as VWXYZ and man is coded as 123, then how would you code RESENTMENT in that language?

(a)YWZW3V1W3Y    (b)YWZ3WV1W3Y   (c)YWZW3V1WY3 (d)YWZW3V1W3V

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Ex. 4. If TEARS is coded as VWXYZ,then how would you code BEASin that language

(a) YWXZ (b) VWX2 (c) MWXZ (d) WVZY.

Soln:

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Baslc’Vord:               T   E   A  R   S
Coded Word:             V  W  X  Y    Z

Using the same coding pattern for BEAS, we get W for E, X for A and Z for S but code for B cannot be determined
as it is absent in the basic word. Now we shall take the help of options. In option (a) we get W, X, Z for E, A and
S, respectively which is correct but coding for B cannot be Y as it is the code for R. Likewise in option (b), V
cannot be coded for B as it is the code for T. In option (c),we see that code for B is Mwhich seems to be correct as it
has not been used as a code for any of the letters in basic word. Hence, code for BEASwould be MWXZ. Therefore,
option (c) is our correct answer.

(B) Substitution in Mixed-up Fashion
Rule applied in this type of questions follow the same pattern as used in type (A)-Direct substitution but with slight modifications. Here, also in this type, each letter of the basic word is substituted for a new letter but it may not necessarily be placed in the same position in coded word as it occupies in the basic word. In simple words, it implies that coded letter at first position in basic word does not necessarily occupy the first position in the coded word. It can be placed at any place in the coded word.

Ex 5    IN a code language, if BEAT is coded as 5642 and SWEET is coded as 66912,how would you code TEASE?
A) 96162 (b) 56264 (c) 96625 (d) 55296

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It is very clear from the coding pattern used in the above question that substitution for the letters has not been
used directly, Code for E seems to be 6 in BEATwhereas it carries code 9 and 1 in the word SWEET which apparently appears to be incorrect because in substitution method same letter carries same code even if It appears in different words. We see that in word SWEET, letter E appears twice and in it’s coding  numeric 6 appears twice. Thus it is confirmed that code for E is 6. It may be concluded from the coding pattern used here that letters of the words BEAT and SWEET have been substituted for numeric in jumbled up form. Word BEAT and SWEET share common letters E and T and their coding share common numeric 6 and 2. Therefore, E is coded as 6 and T is coded as 2. IL means
that the code for TEASEwill definitely have 6,6 and 2 for E, E and T. Code for A and S has yet to be found out.
Now look at the word BEAT and SWEET again, we see that code for A in word BEAT should be either 5 or 4
(leaving 6 and 2 for E and T). Similarily, code for S should be either 9 or 1 (leaving 6 and 2 for E and T). We shall not
take the help of options to answer the code for TEASE.

(a) It cannot be the code for TEASE as code for A (5 or 4) is not available.

(b) It cannot be the code for TEASE as code for S (9 or 1) is not available.

(c) It may be the code for TEASE as besides 662 code for EE and T, we get 5 as probable code for A and 9 as probable code for S. Hence, option (c) is the correct answer.

Category III
In this category, rule of coding is of entirely different type from what has been discussed so far in category I and U. In this type, word is coded, replacing each letter of the word by a new word from the alphabets (A….. Z) on the basis of a particular method. It has further been explained in the following examples.

Ex. 6. If TEMPLE is coded as VHQURL, how would you code CHURCH?

(a) EkYWIO (b) EKUWIO (c) EKYWIN (d) EKYWJO

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Ex. 7. If TEMPLE is coded as VHQNIA, how would you code CHURCH?

(a) EKYWI (b) EKYQZD (c) EKYPZD (d) EKYQWD

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Here, the first half of the letters of the word TEMPLE have been replaced with new letters from the alphabets with a gap of 1, 2 and 3 letters respectively in forward direction, and second half of the letters of the word have been replaced by new letters from the alphabets with a gap of 1, 2 and 3 in backward direction. Hence, code for word CHURCH would be EKYPZD. Hence, (c) is our answer.
We have endeavoured here to incorporate maximum types of questions in the following exercises taking into
consideration the existing pattern of various competitive examinations. In the following exercises questions of all types have been mixed up and given in one exercise instead of giving them separately, category-wise. It has been done to enable the students to use their mind to find as to what rule will be applied for each questions.