12th Class Mental Ability Coding-Decoding Notes - Coding-Decoding

Coding - Decoding

 

 

A ‘code’ is a system of conveying a message through signals. It is a method of sending a message between sender and the receiver in such a way that only the sender and the receiver can know its meaning. However ‘Coding’ is done according to a certain pattern in the mind of the sender. Therefore, its meaning can be deciphered by a third person, only if he carefully studies this pattern. This process is called ‘Decoding’. This capability is important in many fields of application.

Generally letters are coded into numbers according to their position in alphabetical order in backward or forward sequence. The position of letters are shown in the tables given below:

 

Table 1:

            Positions of letters in forward order (Left to Right)

           

A 1

B 2

C 3

D 4

E 5

F 6

G 7

H 8

I 9

J 10

K 11

L 12

M 13

N 14

O 15

P 16

Q 17

R 18

S 19

T 20

U 21

V 22

W 23

X 24

Y 25

Z 26

 

Table 2:

            Positions of Setters in backward order (Right to Left)

 

Z 1

Y 2

X 3

W 4

V 5

U 6

T 7

S 8

R 9

Q 10

P 11

O 12

N 13

M 14

L 15

K 16

J 17

I 18

H 19

G 20

F 21

E 22

D 23

C 24

B 25

A 26

 

 

Table 3:

            Opposite letters

 

           

 

 

Example:

1. If in a certain language, MADRAS is coded as NBESBT, how is BOMBAY coded in that language?  
   

            (a) CPNCBX                  (b) CPNCBZ                    

            (c) CPOCBZ                   (d) CQOCBZ                     

            (e) None of these                                                      

Ans.     (b)

            Explanation: Option (b) is correct because each letter in the word is moved one step forward to obtain the corresponding letter of the cold.                 

             Let us see:

           

                              

 

           

Rest of the options is incorrect because of the correctness of option (b).

 

2. In a certain code, BREAKTHROUGH is written as EAOUHRBRGHKT. How is DISTRIBUTION written in that code?

            (a) TISTBUONDIRI                                 (b) STTIBUONRIDI                

            (c) STTIBUDIONRI                                 (d) RISTTIBUDION                

            (e) None of these

Ans.     (c)

            Explanation: Option (c) is correct.

            Let us divide the letters of the given word into pairs and label these pairs from 1 to 6

 

\[\frac{BR}{1}\,\,\,\,\,\frac{EA}{2}\,\,\,\,\,\,\,\,\,\frac{KT}{3}\,\,\,\,\,\,\,\,\,\,\,\,\frac{HR}{4}\,\,\,\,\,\,\frac{OU}{5}\,\,\,\,\,\,\frac{GH\,}{6}\]

 

Clearly, the code contains these pairs arranged in the order 2, 5, 4, 1, 6, 3. Dividing the letters of the word DISTRIBUTION in pairs, we have:

           

\[\frac{DI}{1}\,\,\,\,\,\frac{ST}{2}\,\,\,\,\,\,\,\,\,\frac{RI}{3}\,\,\,\,\,\,\,\,\,\,\,\,\frac{BU}{4}\,\,\,\,\,\,\frac{TI}{5}\,\,\,\,\,\,\frac{ON\,}{6}\]

 

Arranging these in the order 2, 5, 4, 1, 6, 3, we get the required code i.e. STTIBUDIONRI. Hence, the answer is (c).

 

3. If ‘HGTL’ is coded as ‘DCRJ’, then ‘PEQD’ is coded as..................

            (a) LAOB                      (b) LOAB

            (c) LBOA                       (d) LOBA

            (e) None of these

Ans.     (a)

            Explanation: Option (a) is correct because 1st two letters are coded 4 letters backward and last two letters are two places backward.

 

            Let us see:

 

Similarly,

 

 

          

Clearly, code for ‘PEQD’ is ‘LAOB’.

Rest of the options is incorrect because of the correctness of option (a).

 

Snap Test

 

1. If code for ‘OPPOSITE’ = ‘ETISOPPO’, then code for ‘TOGETHER’ = ‘?’

            (a) REHTGEOT              (b) RETHEGOT

            (c) REHGOET                (d) REHTEGOT

            (e) None of these

Ans.     (d)

Explanation: Option (d) is correct because coding is done in reverse order. When ‘OPPOSITE’ is written in reverse order it becomes ‘ETISOPPO’ and similarly, when ‘TOGETHER’ is written in reverse order, it will become ‘REHTEGOT’.

Rest of the options is incorrect because of the correctness of option (d).

 

2. If ‘KHDFJ’ is coded as ‘PSWUQ’, then how will ‘JPMKH’ be coded?

            (a) QKNPS                     (b) QKNSP

            (c) QNKPS                     (d) QSNPK

            (e) None of these

Ans.     (a)

            Explanation: Option (a) is correct because letters are coded with their opposite letters. (See ‘Table 3’).

 

            Let us see:

 

Similarly,

 

 

           

Clearly, code for ‘JPMKH’ will be ‘QKNPS’.                               

Rest of the options is incorrect because of the correctness of option (a).

 

3. If code for \[\mathbf{WNK}=\mathbf{SJG}\], then code for \[\mathbf{LPG}\text{ }\mathbf{= ?}\]           

            (a) HCL                         (b) LHC

            (c) HLC                         (d) CLH

            (e) None of these                                                     

Ans.     (c)                                                     

            Explanation: Option (c) is correct because letters are coded four places backward.

            Let us see:

 

 

Similarly,

 

 

           

Clearly, code for ‘LPG’ will be ‘HLC.

Rest of the options is incorrect because of the correctness of option (c).

 

4. In a certain code language ‘A’ is coded as 3’, ‘B’ is coded as ‘4’, ‘C’ is coded as ‘5’ and so on, then find the code of ‘FGBEAADC’.

            (a) 89334765                 (b) 89743365

            (c) 89347365                  (d) 89473365

            (e) None of these

Ans.     (d)

            Explanation: Option (d) is correct.

            Let us see:

            According to the question, following are the given codes:

 

           

 

            Now, code for

 

           

Clearly, code for ‘FGBEAADC’ will be ‘89473365’.

Rest of the options is incorrect because of the correctness of option (d)

 

5. If in a certain code, O is written 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 how will COMPANIES be written in that code?

            (a) SMINCPAMO            (b) SEIACPAMO

            (c) SEINCPAMO             (d) SEINCPMIO

            (e) None of these

Ans.     (c)

            Explanation: Option (c) is correct.

            Substituting the letters of the given word with their respective codes, we have:

 

           

 

           

Hence, the answer is (c).

 

6. If MACHINE is coded as \[\mathbf{19}-\mathbf{7}-\mathbf{9}-\mathbf{14}-\mathbf{15}-\mathbf{20}-\mathbf{11}\], how will you code DANGER?

            (a) 11 - 7 - 20 - 16 - 11 - 24         (b) 13 - 7 - 20 - 9 - 11 - 25

            (c) 10 - 7 - 20 - 13 - 11 - 24         (d) 13 - 7 - 20 - 10 - 11 - 25

            (e) None of these

Ans.     (c)

            Explanation: Option (c) is correct.

 

Clearly, every letter is assigned a numerical code obtained by adding 6 to the numeral denoting the position of that letter in the English   alphabet.

Thus, A is coded as \[\left( 1\,\,+\,\,6 \right)\]i.e. 7, B as \[\left( 2\,\,+\,\,6 \right)\] i.e. 8, C as \[\left( 3\,\,+\,\,6 \right)\] i.e. 9 ,...., M as \[\left( 13\,\,+\,\,6 \right)\]i.e 19,....., Z as \[\left( 26+6 \right)\] i.e. 32.

Since, D, A, N, G, E, R are 4th, 1st, 14th, 7th, 5th and 18th letters in the English alphabet, so their respective codes are \[\left( 4\text{ }+\text{ }6 \right),\text{ }\left( 1\text{ }+\text{ }6 \right),\text{ }\left( 14\text{ }+\text{ }6 \right),\text{ }\left( 7\text{ }+\text{ }6 \right),\text{ }\left( 5\text{ }+\text{ }6 \right),\text{ }\left( 18\text{ }+\text{ }6 \right)\] i.e. \[10,\text{ }7,\text{ }20,\text{ }13,\text{ }11,\text{ }24\]. So, the code for DANGER is \[10\text{ }-\text{ }7\text{ }-\text{ }20\text{ }-\text{ }13\text{ }-\text{ }11\text{ }-\text{ }24\].

            Hence, the answer is (c).

 

7. If each of the letters in the English alphabet is assigned odd numerical value beginning \[\mathbf{A}=\mathbf{1},\text{ }\mathbf{B}=\mathbf{3}\] and so on, what will be the total value of the letters of the word INDIAN?

            (a) 86                            (b) 88

            (c) 89                            (d) 96

            (e) None of these

Ans.     (d)

            Explanation: Option (d) is correct.

            Clearly, we have:

 

Letters	A	B	C	D	E	F	G	H	I	J	K	L	M	N
Value	1	3	5	7	9	11	13	15	17	19	21	23	25	27

            So, INDIAN \[=\text{ }1\text{ }+\text{ }N\text{ }+\text{ }D\text{ }+\text{ }1\text{ }+\text{ }A\text{ }+\text{ }N\]    

            \[=\text{ }17\text{ }+\text{ }27\text{ }+\text{ }7\text{ }+\text{ }17\text{ }+\text{ }1\text{ }+\text{ }27\text{ }=\text{ }96.\]

 

8. If code for \[\mathbf{W}=\text{ }\mathbf{18}\], then the code for \[\mathbf{W = ?~~~~~~~~~~~}\]

            (a) 55                            (b) 28

            (c) 14                            (d) 20

            (e) None of these

Ans.     (d)

            Explanation: Option (d) is correct because code is the difference of the positions of letters in backward alphabetical order.

            Let us see:

 

Similarly,

     

             Clearly, code for \[\mathbf{DX}\text{ }=\mathbf{20}\].                                                    

            Rest of the options is incorrect because of the correctness of option (d).            

            Note: See ‘Table 2’ for positions of letters in backward order.