Below are three sample encoding / decoding questions. Most of these questions require you to predict a logic and evaluate it on trial and error basis. Due to the very nature of these questions, solving these require extensive practice.
In a company to maintain fool proof security in message transferring, they were using code language.If the word 'SLUMPS' is coded as '201122121718' , how will they code INSTRUCT ?
a) 101320191920419 b) 101913152817416 c) 151419132171864 d) 241531271816194
Answer : a) 101320191920419
To solve this problem, we have to identify the coding scheme employed for SLUMPS. When no additional hint (other than a sample word and its code) is given, it is better to start by breaking the word into alphabets used and trying to identify a consistent coding scheme.
Let us start by replacing every alphabet of SLUMPS with its position from letter 'A'. (This will be the starting step for most of the problems of this type). i.e S is the 19th alphabet from A and hence will be replaced by 19, L is the 12th alphabet from A and hence will be replaced by 12 and so on.
So SLUMPS will yield 191221131619. This is our intermediate step and the most important one. At this step you have to try to compare the obtained intermediate code with the actual code given in question. i.e 191221131619 should be compared with 201122121718
Closely observing you will be able to find out a scheme. In this case, 1 has been added to odd place digits of the intermediate code and 1 is subtracted from even place digits of the intermediate code to get the actual code. (illustration is given below)
19 12 21 13 16 19
+1 -1 +1 -1 +1 -1
20 11 22 12 17 18
Now we have to apply our hard found logic to INSTRUCT , which will yield 101320191920419
In a language EMPLOYEE is coded as 101332121550510 then what will be the code for PERSON ?
a) 31245651715 b) 32536193014 c) 32645187127 d) 25475121415
Answer : b) 32536193014
Let's find the logic used to code EMPLOYEE. (This logic is bit different from that of the first question)
Split the word EMPLOYEE into two half's EMPL and OYEE
Replace alphabets of EMPL and OYEE with their respective numbers when counted from A.
Thus EMPL and OYEE will yield 5 13 16 12 and 15 25 5 5 as intermediate codes.
In the intermediate code for EMPL, numbers (not digits) in odd places i.e 5 and 16 are doubled while numbers in even places are left undisturbed. Thus EMPL will yield 10 13 32 12
In the intermediate code for OYEE, numbers in even places are doubled while numbers in odd places are left undisturbed. Thus OYEE will yield 15 50 5 10
Joining the above obtained intermediate codes, we will get 101332121550510 which is the code for EMPLOYEE.
If the above logic used, we will get 32536193014 for PERSON.
Read the following codes carefully and answer the question.
i) " Milk is white in color" coded as 52360
ii) " White represents peace " coded as 379
iii) " Milk contains calcium " coded as 248
What is the code used for the word 'Color' ?
a) 2 b) 6 c) 5 d) Can't be determined
Answer : d) Can't be determined
White is common across first and second statements. Common code across first and second codes is 3. Hence 'White' should have been coded as 3.
Similarly observing first and third statements and comparing their codes, one can conclude that 'Milk' would have been coded as 2.
Thus 3 and 2 cannot be the codes for 'Color'. Digits left out in the code 52360 are 5, 6 and 0. But there is no sufficient data to shortlist one final digit as the code for 'Color'. Hence answer is option d.
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