Number Sequence

In the number sequence questions, a series of numbers is given and questions based on this series are to answered by the candidate. The number sequence may sometimes contain alphabet an alphabet sequence or a symbol sequence. Usually, the number sequence questions will ask you to find the positions of a few numbers, count a specific type of numbers in the sequence and so on. Here we will see all the expected types of such questions. We will also solve many examples that we expect can appear in the exam from this section.

Suggested Videos

 

Number Sequence

In these questions, a random grouping of numbers is present. Sometimes this forms a sequence and sometimes it is just a random collection of numbers, symbols, and alphabets. Following the series, questions that ask you about the position, number and symmetry of these numbers, symbols, and alphabets will be present. This is a quick check of your mental presence if anything. It is recommended that you write down the sequence and the position of its various terms. Let us see a few examples of this type and understand how the questions from the section may look.

                                                                                                                                              Source: Youtube.com

Example 1: In a row of trees, one tree is fifth from either end of the row. How many trees are there in the row?
A) 9                        B) 15                       C) 10                         D) 11

Answer: The easiest way to do it is to mark dots on the paper and count from the beginning. When you reach a count of five, start counting backward to 1. Once you reach the count of 1, start counting the entire collection of dots again. You will see that there are a total number of 9 dots. So the correct option here is A) 9.

Another method is the simpler one and will save you time. Since the count has to be five from either side, we can write 4 + 1 + 4 = 9. Therefore we see that the answer is A) 9.

Example 2: Study the following sequence of care and answer the questions that follow:

& ( 8 2 F 4 8 H  % # & < % 6 J 5 # ! 2

Q 1: How many such numbers are there in the above sequence that are immediately followed by a symbol and also immediately preceded by a letter?

A) 1             B) 0                 C) 3                 D) 2

Answer: There is a total of 19 terms in the above arrangement. Out of these terms, there is a total of 7 numbers and the rest are alphabets or symbols. Here we have to find out those numbers that are followed by a symbol and which follow a letter.  In the above sequence, 5 is followed by a symbol and preceded by a letter or an alphabet. None of the other numbers follows this kind of rule so the answer is 1. Therefore, the correct option is A) 1.

Q 2: How many symbols occupy odd positions in the above sequence?

A) 4                  B) 5                         C) 6                              D) 7

Answer: A careful counting will tell you that there are exactly 5 such symbols that occupy an odd position in the above sequence.

Q 3: How many symbols are followed by letters?

A) 0                         B) 1                            C) 2                              D) 3

Answer: There is no such symbol in the sequence so the answer is A) 0.

Some More Solved Examples

Example 3:  If Malik finds that he is twelfth from the right in a line of the boys and fourth from the left, how many boys should be added to the line such that there are 28 boys in this line?
A) 15                B) 12                   C) 17                           D) 13

Answer: Here again we can use both the methods. Go on making dots starting from the right until you reach 12 and then count down from 4 to 1. Now count the total number of dots. You will see that there is a total of fifteen dots. In other words, the row has about 15 boys in it. The answer is A) thus? No, read the question again. The question is asking us to find the number of boys that we shall be adding to this row so that there is a total of 28 boys. Therefore the answer is 28 – 15 = 13. Thus D) 13 is the correct answer.

Using another method, we can write that since he is 12th from right and 4th from left, that means after Malik there are 3 boys that follow him in the row. Therefore, the total number of boys in this row = 12 + 3 = 15. Thus we have 28 – 15 = 13 and the option is D) 13 again.

Example 4: In the following series, how many fours are there that are preceded by the number seven and don’t precede the number three: 5 9 3 2 1 7 4 2 6 9 7 4 6 1 3 2 8 7 4 1 3 8 3 2 5 6 7 4 3 9 5 8 2 0 1 8 7 4 6 3?

A) 3                        B) 4                         C) 5                          D) 9                           E) 12

Answer: Let us try to understand the question first. Here we have to find all those 4s that have 7 before them and don’t have a 3 following them. Numbers like 7 4 2, 7 4 6, 7 4 1, 7 4 6. Therefore the answer is B) 4.

Practice Questions

Q 1: In some queue, Jagannath is 10th from the front while Amit is 25th from behind and Maroof is just in the middle of the two. If there are 50 people in this queue. What position does Maroof occupy if we count from the front?

A) 12th                  B) 14th                 C) 16th                  D) 18th

Ans: D) 18th

Q 2: Study the following sequence carefully and answer the questions that follow:
3 D K $ P 2 7 # @ 4 J T H 9 * F M R 1 5 % ? 6 8
How many numbers from the above series are there which are immediately followed by a symbol and also immediately preceded by a letter?

A) 1                        B) 2                        C) 3                       D) 4

Ans: A) 1