Order & Sequencing

In these type of questions, you have to study a given number, alphabet series or data related to ranks (position) and answer questions based on that. Usually, the questions are based on finding a particular pattern or finding rank of a particular person.
In this, broadly there are two categories:
1. Number Test
Example 1 : How many 6s are there in the following number sequence which are
8 6 6 10 5 6 8 7 5 6 10 9 8 6 7 8 7 5 4 3 6 7 8 9
Solution: In this series, you are looking for a group consisting of 6, followed by 7 i.e. 67, which is preceded by 8 i.e. 8 appears before 6. Hence, the complete number becomes 867. Thus in the given series, 8 6 6 10 5 6 8 7 5 6 10 9 867 8 7 5 4 3 6 7 8 9, the required sequence appears once.
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Example 2 : How many even numbers are there in the following series of numbers, each of which is immediately preceded by an odd number, but not immediately followed by an even number?
6 4 5 9 10 8 2 7 6 4 3 10 9 8 4 6
Solution: You are looking for a group of OEO (odd, even, odd) numbers. Thus, in the given series, 6 4 5 9 10 8 2 7 6 4 3109 8 4 6, the required sequence appears only once.
Example 3 : If the first half of the given series is reversed, which of the following will be the third digit to the left of the third digit from the right?
6 2 10 4 7 5 3 9 8 2 6 9 9 4
Solution: The series after reversing the first half will look like
3 5 7 4 10 2 6 9 8 2 6 9 9 4
Firstly, count the final position of the digit i.e. third digit to the left of the third digit from the right will be 3 + 3 i.e. 6th digit from right. Now, find the digit at sixth place from the right, which is 8 and hence that becomes your answer.
2. Ranking Test 
In these type of questions, the rank of a person, both from the top and/ or from the bottom are mentioned and the total number of persons is to be calculated.
Example 4: A class of boys is standing in a single line. One boy is thirteenth from the left-hand side as well as from the right-hand side. How many boys are there in the class?
Solution: A class of boys is standing in a single line. One boy is thirteenth from the left-hand side as well as from the right-hand side. How many boys are there in the class?
Let us directly use the formula
Total number of persons in a row or class = (Rank of a person from upper end or left end) + (Rank of that person from lower or right end) - 1
So, the total number of boys in the class in this case will be = (13 + 13 –1) = 25.
Total number of persons in a row or class = (Rank of a person from upper end or left end) + (Rank of that person from lower or right end) - 1 So, the total number of boys in the class in this case will be = (13 + 13 –1) = 25.
Example 5: P and Q are ranked sixth and tenth respectively from top in a class of 30 students. What are their respective ranks from the bottom in the class?
Solution: Let us use the formula
Rank of a person from lower or right end = (Total number of persons in row) - (Rank of that person from upper or left end) + 1 P’s rank from bottom will be = 30 – 6 + 1 = 25 Q’s rank from bottom will be = 30 – 10 + 1 = 21
Example 6: In a class of 32 students, David ranks 6th from the bottom. What is his rank from the top?
Solution: Applying the same formula as explained above.>

David’s rank from top will be = 32 – 6 + 1 = 27th

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Order & sequencing: Key Learning
  • Total number of persons in a row or class = (Rank of a person from upper end or left end) + (Rank of that person from lower or right end) - 1
  • Rank of a person from lower or right end = (Total number of persons in row) - (Rank of that person from upper or left end) + 1