Strategy to Solve Machine Input Output Questions

 Introduction: A sequence either in the form of a sentence or in number forms is given. This is called the INPUT. This INPUT is followed by a number of steps. In these steps, the input is arranged in different ways. You being the candidate is required to trace out the ways or patterns in the given arrangement and then determine the desired output step, according to as is asked in the questions.

The theory above in the form of question looks like:

INPUT: day step amiss to block inside
Step 1: amiss day step to block inside
Step 2: amiss block day step to inside
Step 3: amiss block day inside step to
This is followed by about 5 question based on several different inputs and needed to be solved using the logic applied in the given input.
Now, let’s talk about the logic applied in the above example.
When you keenly observe the above input and the steps, with each progressing step the words are arranged in the ascending order of the first letter of the word. The word is just shifted forward and the rest of the sequence remains same and so on. This shifting is called OPERATION.

There are basically four types of operation

1. Shifting – In this pattern, we usually shift the given words or numbers of given input as per fixed pattern.
2. Arranging – In this pattern, the words or numbers are arranged as per a fixed order. This order can be an alphabetical order in case of words, increasing or decreasing in case of numbers.
3. Arithmetic – In this pattern, the input consists of some numbers. The subsequent steps are obtained by taking the numbers of input and performing different arithmetic operations
4. Miscellaneous – As the name suggests, the combination of any operations. The input can be anything and the machine can perform a set of random operations on it.

A few tips to identify the type of operation.

Tip – 1: If the input and the subsequent steps involve the same words (or numbers) then it is most likely to be a problem of either shifting or arrangement. Else if the words (or numbers) change in subsequent steps it is a problem of arithmetical operation or miscellaneous type.
Tip -2: If either the first or the last word (or number) of all the steps (excluding input) remains unchanged then it is (almost) certain that it is an arrangement problem.
Now let us see if you can identify the type of operation.

Identify the type of operation for following examples:

E.g. 1 –
Input: Sherry quart pint bar
Step 1: quart sherry pint bar
Step 2: quart sherry bar pint
Step 3: sherry quart bar pint
Step 4: sherry quart pint bar
Step 5: quart sherry pint bar

E.g. 2 –
Input: 12 14 5 18 13
Step 1: 3 5 5 9 4
Step 2: 36 42 15 54 39
Step 3: 169 225 36 361 796
Step 4: 24 28 10 36 26

E.g. 3 – 
Input: gone are the days of yore
Step 1:are gone the days of yore
Step 2: are days the gone of yore
Step 3: are days gone the of yore
Step 4:are days gone of the yore

And the answers are as:
E.g. 1 – Shifting
E.g. 2 – Arithmetic
E.g. 3 – Arrangement
If you got all of them right means you are getting it.
Now let’s dig the topic a little deeper. Shall we!


When you have determined that the operation in the question is shifting and the shifting of letters, rather than playing with alphabets which is a tad complicated, number the alphabets in the input and continue with the numbers which makes the task a little easy.
For example:
Input: cry an fire pull tee ant see
Step 1: see an pull fire tee ant cry
Step 2: an pull cry tee fire see ant
Step 3: ant pull tee cry fire see an
Step 4: pull tee an fire cry ant see
And so on goes the machine. Study the logic and answer the questions that follow. 
Solution: The classic sign to determine the operation SHIFTING in the question is the word “so on” at the end of the question. If the operation in the question would be ARRANGEMENT, the question might say something like “step xx is the last step.”
But as in the above example ther, is no mention of the last step and the input consists of alphabets only, the options for operation being ARRANGEMENT and ARITHMETIC are eliminated, Thus leaving us with SHIFTING operation.

Now to make things easy, I number the words in the input as:

So, playing with the steps with the numbers we assigned

Wasn’t that easy! Based on the above steps, we can easily answer all the questions. Let’s say

Question 1:

If step 13 of a given input be “blut ne fur sur say trep dawn”, what is the 17th step of the input?
1) sur say ne blut trep for dawn
2) blut say sur ne dawn trep fur
3) dawn ne trep sur fur say blut
4) sur ne dawn blut say fur trep
5) None of these
Solution: As step 13 is an odd number and the changes in the steps also seem to follow the changes in the odd-even pair, we number the step 13 alphabets as in step 1, which will look like


Just a little practice and you will get a hang of it.

Few Practice questions:
Input: software scrips are red hot in bourses
Step 1: software in are red hot scrips bourses
Step 2: red are in software bourses scrips hot.
Step 3: in are red hot scrips bourses software
Step 4: in bourses red hot scrips are software
And so on. As per the rule followed in the above steps, answer the following questions.

Q 1: Input: the sudden need to alter policy stems
Which step would be “policy stems to alter sudden need the”

Q 2: If step 4 of an input is “none of the players have turned India”, what would be step 9?

Q 3: Input: most of the players were given approvals
What will be the 4th step for this input?

Q 4: If step 5 of an input is “none of this has happened at all”, what will definitely be the input?

Q 5: 
If step 1 of an input is “in this form of trading by amway”, what would be step 7 of the input? 


Let’s study this operation with an example
Input: 85 16 36 04 19 97 63 09
Step 1: 97 85 16 36 04 19 63 09
Step 2: 97 85 63 16 36 04 19 09
Step 3: 97 85 63 36 16 04 19 09
Step 4: 97 85 63 36 19 16 04 09
Step 5: 97 85 63 36 19 16 09 04
For given input Step 5 is the last step.

Solution: As we discussed before, the mention of last step in the question indicates that the operation used on input must be ARRANGEMENT.
When we observe the question closely, the numbers are arranged in a descending order step by step. The biggest number in the series is pulled forward, then the second largest and so on. Thus giving us the list sorted in decreasing order at last.

Now let’s move to the questions based on arrangement mentioned above.

Question 1:

Which of the following will be step 5 for the given input?
Input: 25 08 35 11 88 67 23
Solution: As we know the logic we need to apply, we determine the steps one by one, which goes like
Step 1: 88 25 08 35 11 67 23
Step 2: 88 67 25 08 35 11 23
Step 3: 88 67 35 25 08 11 23
Step 4: 88 67 35 25 23 08 11
Step 5: 88 67 35 25 23 11 08

This might take about a minute or two. Let’s move to a quicker method


In the above diagram, rather than writing the entire step, we just draw a curved line from the number that needs to be accessed to the front of the line and give them a number to indicate the step number, as we know the final arrangement to be descending.
You must be wondering that before arranging 23, number 25 must be shifted forward. You are right absolutely, but as 25 is already in front which means has been automatically set to the place it needs to be, thus hinting us to leave it and work on the next number, which in this case is 23.
This is also the case with number 8 which comes in the front where it needs to be thus saving us a step.
Therefore the output after 5 steps looks like
88 67 35 25 23 11 08 

A point to remember in case of ARRANGEMENT

  • In arrangement problems, the contents of an earlier step can never be determined with certainty. 
Let’s work with another example to perfect this trick. 


Input: as if it on an zoo figure of in at
Step 1: an as if it on zoo figure of in at
Step 2: an as at if it on zoo figure of in
Step 3: an as at figure if it on zoo of in
Step 4: an as at figure if in it on zoo of
Step 5: an as at figure if in it on of zoo
And Step 5 is the last step for this input.
Observing the last step, the words are arranged in alphabetical order based on the first letter step by step.

Question 1:

Which of the following will be step 2 for the given input?
Input: am ace all if is
1. ace all am is if
2. all am ace if is
3. is if am ace all
4. ace all am if is
5. None of these

Therefore after 2 steps, the series looks like,
ace all am if is (which is option no 4).

Question 2: 

Input: you are at fault on this 
Which of the following steps would be – are at fault on you this?
1. Step 1
2. Step 2
3. Step 3
4. Step 4
5. Step 5

Question 3:

Input: him and his wither or her
Which step will be the last step for this input?
1. Step 1
2. Step 2
3. Step 3
4. Step 4
5. Step 5

Question 4: 

Step 4 of an input looks like – an apple at cot was red on one side
Which of the following will definitely be the input?
1. was cot red an on at one apple side
2. cot an at apple was red on one side
3. apple at an cot was red on one side
4. Cannot be determined
5. None of these
These are a few practice questions for arrangement based on above logic.
Moving forward, up until now, all the inputs we saw had either numbers or alphabets. What if the input was a combination of both alphabets and numbers?
Why not take an example to understand it clearly!


Input: trucks 49 carry 36 massive 25 load 16
Step 1: carry trucks 49 36 massive 25 load 16
Step 2: carry 16 trucks 49 36 massive 25 load
Step 3: carry 16 load trucks 49 36 massive 25
Step 4: carry 16 load 25 trucks 49 36 massive
Step 5: carry 16 load 25 massive trucks 49 36
Step 6: carry 16 load 25 massive 36 trucks 49
Step 6 is the last step for the above input.
Answer the following questions based on the above rearrangement.
Solution: When we observe the input, it consists of both numbers and words. Having observed the input, final step has the input arranged in “word number word number” format that too following the ascending order for both words(according to first alphabet) and number.
When we jump from input to step 1, only one element (either word or number) is arranged which means one step processes on only one element. Let us now move forward to the questions.

Question 1:

If the third step of the input is
Step 3: is 4 material 36 test 16 packed 64
What will be the Step 5?
1. is 4 material 16 packed 64 test 36
2. is 4 material 16 packed 36 test 64
3. is 4 material 16 test 36 packed 64
4. There are only 4 steps
5. None of these
As we discussed right after looking at the question, each step works on one element. Now as the step provided to us in the question is step 3, which means 3 steps must have worked on 3 elements, thus arranging 3 elements in the desired format.(which is also evident if we look at the step)
Now, as for further steps, rather than each and every step individually, we write the step once and use curved lines to show the movement, which looks like


I have replaced the words in the step 3 as
“is” with “I”, “material” with “m”, “test” with “t” and “packed” with “p”
Which saves us the trouble of writing the entire word coz as I always say “Sahi question karne se jyada important hai sahi time me sahi question karna”.
As you can see after working on the given series for 2 more steps, the output would look like
Step 5: is 4 material 16 packed 36 test 64
Which is option no 2, thus the answer.
Let us now solve one more question based on above operation.

Question 2:

Input: the 36 issue 49 became 9 serious 25
How many steps will be required to complete the rearrangement?
1. Three
2. Four
3. Five
4. Six
5. None of these
Solution: Let us now take the input and a pen for the curved lines. Always remember when the next element to be worked on is already in front of the line, it means it is already arranged and doesn’t require moving. Skip that step and move on to next element.
Also to save some valuable seconds, you can use just the first letter of the word. Don’t forget to use more than one alphabet if two words in the series have same first alphabet.


As “t” is next element to be worked on but is in front, therefore no step required.
Similarly, 49 is the next element which follows “t” thus setting it automatically at the desired position.
Therefore, total number of steps required is 6, which is option no 4.

Few practice problems based on above arrangement

Question 3:

What will be the input if the fourth step of the arrangement is?
Step 4: most 16 people 25 similarly 81 think 36
1. most 25 people 16 similarly 81 think 36
2. most 25 people 16 think 81 similarly 36
3. most 16 people 25 think 36 similarly 81
4. Cannot be determined
5. None of these

Question 4:

What will be the Step 3 for the input?
Input: ministers 25 solved 36 their 81 problems 64
1. ministers 25 problems 36 solved 81 their 64
2. ministers 25 problems 36 solved 64 their 81
3. ministers 25 problems 36 their 81 solved 64
4. ministers 25 solved 36 problems 81 their 64
5. None of these

Moving forward, up until now in all the questions, each step shifted just one element in the series. What if, one step works on more than one element!
Let us try to explore this with an example,


Input: sine 88 71 cos theta 14 56 gamma delta 26
Step 1: cos sine 71 theta 14 56 gamma delta 26 88
Step 2: delta cos sine theta 14 56 gamma 26 88 71
Step 3: gamma delta cos sine theta 14 26 88 71 56
Step 4: sine gamma delta cos theta 14 88 71 56 26
Step 5: theta sine gamma delta cos 88 71 56 26 14
Step 5 is the last step of the rearrangement.
As per the rules followed in above steps, find out in each step of the following questions the appropriate steps for the given input.
Input: for 52 all 96 25 jam road 15 hut 73 bus stop 38 46
As you can see, in the above arrangement question, after every step position of two elements gets changed. Observing the last step closely, we can conclude that the words are arranged in descending order from left to right and so are the numbers.
In the first step, the word with the smallest first alphabet is shifted to the first position simultaneously the largest number is shifted to the last position. The words arranged in the first step shifts to rightward direction in the next step, while the numbers are shifted to leftward direction.
Now let us proceed to the questions based on the arrangement and the provided input.
We can either write all the steps individually or save us some time by doing everything using our favorite curved lines. Let’s take a look


I have replaced the words with only their first letter. You also need to keep in mind the final arrangement which means the last step.

Now to the questions

Question 1:

Which word/number would be at 8th position from the right in step 4?
1. 15
2. road
3. hut
4. jam
5. stop
Solution: Now, as know that in every step two elements get arranged one word to the left side and one number to the right side and with each progressing step, the get shifted inwards. In the question, we are asked about an element from right side in step 4 this means there are total 4 numbers totally arranged from right side occupying 4 positions.
As the elements are shifted inwards, the numbers initially at the right hand corner keep moving inside.
Now, observe closely, we already have 4 numbers arranged; we are trying to figure out elements at the 5th position from right side.
Last number 46 in the input got arranged in step 4.
Next element in the input is 38 which gets arranged in step 5 and so occupies the 5th position from right in the step 4.
Next element “s” which is short for “stop” is arranged in step 7 and so its position remains unchanged in step 4 and takes 6th position from right.
The next two elements “b” as in “bus” and 73 were arranged in step 2 and are already at their desired positions.
Next from right is “h” which is “hut” was arranged in step 4 and so is at desired position.
Moving forward, the next element is 15 which is arranged in step 7th and so remains unchanged in step 4 making it 7th element from right in step 4.
Next element “r” short for “road” is arranged in step 6, leaving it unchanged in step 4 and makes 8th element from right which is also the element for us to determine.
And so the answer to the question “8th element from right in step 4” is “road”, which is option no. 2.
If you find it hard just go through it one more time, you will find it time saving once you have solved a handful of questions using the technique. Let us solve one more question based on above logic and input

Question 2:

Which step number would be the following output? 
bus all for 52 25 jam road 15 hut stop 38 46 96 73
1. There will be no such step
2. Step 3
3. Step 2
4. Step 5
5. Step 6
Solution: As we can see two elements from the left and also two from the right are at the positions as required in the output, thus making it step 2. But before marking your answer, do check the positions of all the other elements other than the two leftmost and rightmost ones. The positions of all the other elements must be unchanged and should be the same as was in the input.
Having checked that, mark the answer. In this case, the position of all the other elements is appropriate thus making option 3 which is step 2, out answer.
Few practice problems based on above logic and input

Question 3:

Which of the following would be step 7? 
1. stop road jam hut for bus all 15 96 73 52 46 38 25
2. road jam hut for bus all stop 15 25 38 46 52 73 96
3. stop road jam hut for bus all 96 73 52 46 38 25 15
4. jam hut for bus all 25 road stop 15 96 73 52 46 38
5. There will be no such step 

Question 4:

Which word or number would be at 6th position from the left in Step 5? 
1. 25
2. stop
3. jam
4. all
5. road

Question 5:

Which of the following would be Step 3? 
1. hut for bus all 25 jam road 15 stop 38 96 73 52 46
2. for bus all 25 jam road 15 hut 38 stop 96 46 73 52
3. hut for bus all jam road 15 stop 38 96 73 52 46 25
4. for bus all 25 jam road 15 hut stop 38 46 96 73 52
5. None of these
I am gonna say it again, tad bit of practice and machine input output questions will be your forte. Try a few questions using tricks mentioned above and save some valuable seconds in the exam which you can utilize letter to add another precious mark in your score.

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