Coding and Decoding - Shortcuts
Code : A code is a a system of words, letters, figures,
numbers or symbols used to represent a message or record information especially for the purposes of secrecy or in
a shorter form
Coding : A system of signals
used to represent letters or numbers in transmitting messages. It is is a method
of transmitting a message between the sender and the receiver such that no
other person can understand the message. We can also call this process as
encoding
In coding, actual letters/ numbers /
words/ symbols are replaced by certain other letters/numbers/words/symbols etc.
To solve the question on coding, students
have to detect (find ) the rule used in the coding and then answer the question
Decoding : Decoding is the
reverse of encoding. It is a method of finding the meaning of something that has
written in the code.
Kinds of Coding-
Decoding questions:
Letter Coding :
Method of Letter
Coding:
a) Skipped over the
letter in forward and backward direction
Example: The word ‘SECRET’ is coded as
‘TFDSFU’. How will ‘TRANSMIT’ be coded ?
Explanation: Here compare each
letter of word and coded word.
S+ 1 =T E+1=F C+1=D
R+1=S E+1=F and T+1 =U
In the same way, TRANSMIT will be coded
as
T+1=U
, R+1=S ,A+1=B , N+1=O , S+1=T , M+1=N , T+1=U
So , TRANSMIT will be coded as USBONU
Example 2 : In a certain language,
KAKINADA is coded as JZJHMZCZ . How is ANDHRA is coded in that language?
Explanation: Clearly, we can see
that each letter of the word KAKINADA is moved one step backward to get the the
code.
K-1 = J , A-1= Z , K-1=J , I-1=H, A-1=Z , D-1=C , A-1=Z
Similarly, ANDHRA is coded as =>
A-1=Z, N-1=M , D-1=C, H-1=G,R-1=Q , A-1=Z
SO ANDHRA will be codes as ZMCGQZ
b) Writing the letters
of given word in reverse order in part or in whole.
Example : In a certain code language,
SHARMA is written as AMRAHS. How will VASUDHA be written in the code?
Explanation : Clearly, when
SHARMA is coded, all letters are revered.
Similarly the code word for VASUDHA is
AHDUSAV.
Example 2 : In a certain code, SUDHEER is
DUSHREE . What is the code word for SRAVANI?
Explanation : Here in this coding
and decoding questions, SUDHEER is written as DUSHREE.
Clearly, we can observe first 3 letters
are reversed , middle letter kept in the same place and last three letters are
reversed.
Similarly , the first three letters are
SRA are reversed as ARS , middle letter kept as before and last 3 letters ANI
are reversed INA.
So the code word for SRAVANI is ARSVINA
c)In few question of
coding and decoding , codes may be the position of those letters in the
alphabet
Example : In certain language, EARN is
coded as 511814. What is the code for SICK in the same language ?
Explanation: Here , the position
of each letter in alphabet is written as code.
The position of E is in the alphabet is 5
, A=1 , R=18 and N=14.
Similarly, the code word for SICK is ,
S=19 I=9 C=3 K=11
The code word for SICK is 199311
Number Coding :
Number coding and
decoding involves two kinds of cases
a) Numerical code
values are assigned to a word.
Example : If C=3 , BAT=23 then the code
for RAHUL?
Explantion: Clearly in the given code, C=3 . So
position of the letter in the alphabet is written
BAT = 23 => B =2 , A=1 and T=20. All
positions are added 2+1+20 =23
Similary , RAHUL = 18 + 1 + 8+21+12 =60
Therefore, the code for RAHUL is 60
b) Alphabetical code
letters are assigned to the numbers
Example : In a certain code 17286 is
written as AIBZJ and 3459 is written as YGUN. How is 12345 is written in the code?
Solution : Here letters are assigned to each number.
From the first one 1=>A , 7=>I , 2=>B , 8 =>z
, 6=>J
And from the second one 3=>Y, 4=>G,
5=>U and 9=>N
The in the same coded language , 1=A ,
2=B , 3=Y , 4=G and 5=U
Therefore , the 12345 is written as ABYGU
in the code language.
Substitution Coding
:
In these type of
coding and decoding reasoning questions, different objects are assigned code
names.
Example: If Sky is called Earth , Earth
is called Moon , Moon is called Pen ,Pen is called River and River is called Sun. Which of the
following is used for writing ?
a)Earth b)Pen c)Moon d)River
Explanation: We know, pen is
used for writing.
Here, pen is called River.
Therefore, River is used for writing in
this code language.
Answer d is the correct answer
Mixed Letter Coding:
In this kind of coding and decoding
questions, three or more sentences are given in the coded language and the code
for a particular word is asked. These sentence consists of 3 or more words .To
find the code for particular word ,take
two sentences having a common word and the common code word will give that
word. We can find the code word for each word of given sentences similarly.
Example : In a certain code language , “ dit
par la” means “ I love you “, “par mat do “ means “ love is good” and “ ka mat par”
means “ love is great”. In that language, which word stands for “ great” ?
Explanation:
Take first two sentences, the common word
is love and common code word is par. So ‘Love
‘ stands for ‘ par’
In last two sentences , the code word ‘mat’
is common and the word ‘ is ‘ common , so is ‘stands’ for ‘mat’.
So , in the third sentence ‘ ka mat par ‘
, the remaining code word ‘ka’ stands
for ‘great’