Number Seriese
Category : 6th Class
Number Series
Learning Objectives
What is a Number Series?
A number series is a sequence of numbers which follow a particular rule. Each element of a series is called a 'term'. In this chapter, we will analyse the pattern of different kind of number series that a particular series follow and find the missing term to continue the pattern.
Example
Find the missing term in the given series.
2, 8, 32, 128, __.
(a) 512 (b) 510
(c) 516 (d) 520
(e) None of these
Answer (a)
Explanation: Option (a) is correct. The relationship between the terms or the pattern that the given series follows is as below.
Therefore, the next term or missing term of the given series will be
Find the missing term in the following number series.
2, 3, 5, 7, 11, 13__.
(a) 15 (b) 19
(c) 17 (d) 14
(e) None of these
Answer (c)
Explanation: Option (c) is correct. The given number series is the sequence of consecutive prime number. So, the next number or the missing term will be 17,
Commonly Asked Questions
Find the next number.
64, 32, 16, 8, __
(a) 2 (b) 4
(c) 6 (d) 0
(e) None of these
Answer (b)
Explanation: Option (b) is correct because in the given number series, each number is half of its previous number. So the required number or the missing term will be 4.
Rest of the options is incorrect because of the correctness of option (b).
What comes in place of question mark (?) in the series given below?
1, 4, 10, 19, ?
(a) 30 (b) 31
(c) 32 (d) 33
(e) None of these
Answer: (b)
Explanation: Option (b) is correct because the series goes as following-
So the required next term in the series will be
Rest of the options is incorrect because of the correctness of option (b)
A single number series can have more than one series.
Example
Look at the following:
(i) 1 4 2 5 3 6
Clearly,
1st series: 1 2 3
2nd series: 4 5 5
(ii) 4 9 5 3 6 8 7 2 8 7 9 1
Let us see:
Here,
1st series: 4 5 6 7 8 9
2nd series: 9 8 7
3rd series: 3 2 1
Commonly Asked Questions
Find the missing number in the following series
8 2 9 1 10 0…………..
(a) 12 (b) 11
(c) 3 (d) 5
(e) None of these
Answer (b)
Explanation: Option (b) is correct.
Let us see:
Rest of the options is incorrect because of the correctness of option (b).
What comes next in the following series?
9 4 8 6 7 8………..
(a) 6 (b) 9
(c) 5 (d) 4
(e) None of these
Answer (a)
Explanation: Option (a) is correct.
Let us see:
Rest of the options is incorrect because of the correctness of option (a).
A number series may have some arithmetical signs also.
Example
Look at the following:
(1) 
(2) 
Commonly Asked Questions
What comes in place of the question mark (?)?
(a) 
(b) 
(c) 
(d) 
(e) None of these
Answer (b)
Explanation: Option (b) is correct because in the given series, 4 is multiplied by 1, 2, 3 and 4 respectively.
Rest of the options is incorrect because of the correctness of option (b),
What comes in place of the blank space?
(a) 
(b) 
(c) 
(d) 
(e) None of these
Answer (c)
Explanation: Option (c) is correct because in the given series, 3 is divided by 5, 6, 7 and 8, respectively.
Rest of the options is incorrect because of the correctness of option (c).
Types of Problems
Problems Based on Addition
Such series are based on addition of numbers.
Example 1
1, 2, 3, 4…….
Series pattern: 1 is added to every number to get the next number.
Example 2
3, 5, 7………….
Series pattern: 2 is added to every number to get the next number.
Commonly Asked Questions
Find the next number in the following series.
0, 2, 4, 6……..
(a) 8 (b) 3
(c) 5 (d) 7
(e) None of these
Answer (a)
Explanation: Option (a) is correct because the series goes as following:
Rest of the options is incorrect because of the correctness of option (a).
What will come in place of the blank space?
1, 10, 19____
(a) 28 (b) 29
(c) 30 (d) 31
(e) None of these
Answer (a)
Explanation: Option (a) is correct because the series goes as following:
Therefore, the required number will be 
Rest of the options is incorrect because of the correctness of option (a).
Problems Based on Substraction
Such series are based on subtraction of numbers,
Example 1
4 3 2 1
Series pattern: 1 is subsaturated from every number to get the next number.
Example 2
7 5 3 1
Series pattern: 2 is subsaturated from every number to get the next number.
Commonly Asked Questions
Find the missing number in the series given below.
9 6 3 ______
(a) 8 (b) 2
(c) 7 (d) 0
(e) None of these
Answer: (d)
Explanation: Option (d) is correct because the series goes as following
Rest of the options is incorrect because of the correctness of option (d).
What comes next in the given series?
20, 19, 17, 14, 10,_____
(a) 4 (b) 3
(c) 5 (d) 1
(e) None of these
Answer (c)
Option (c) is correct because the series goes as following:
Therefore, next number in the series will be
Rest of the options is incorrect because of the correctness of option (c).
Problems Based on Multiplication
Such series are based on multiplication of numbers.
Example 1
1 2 4 8
Series pattern: Each element is multiplied by 2 to get the next element.
Let us see: 
Example 2
Series pattern: Each element of the series is a multiplication of same numbers and the numbers taken for this multiplication are in forward or increasing order sequence.
Commonly Asked Questions
What comes next in the given series?
(a) 
(b) 
(c) 
(d) 
(e) None of these
Answer (c)
Explanation: Option (c) is correct because 3 is multiplied by 1, 2, 3, 4 and 5, respectively.
Rest of the options is incorrect because of the correctness of option (c).
Find the missing number.
2, 6, 8, 10, 12,
(a) 3 (b) 1
(c) 4 (d) 7
(e) None of these
Answer (c)
Explanation: Option (c) is correct because the series goes as following:
Rest of the options is incorrect because of the correctness of option (c).
Problems Based on Division
Such problems are based on division of numbers.
Example 1
Series pattern: 1 is divided by 1, 2, 3 and 4, respectively.
Example 2
Series pattern: 4 divides 2, 3 and 4, respectively.
Commonly Asked Questions
Fill in the blank with suitable option
(a) 
(b) 
(c) 
(d) 
(e) None of these
Answer (b)
Explanation: Option (b) is correct because in the given series, 8 divides 5, 6, 7, 8 and 9, respectively. Hence,, after dividing 7, 8 will definitely divide 8,
Rest of the options is incorrect because of the correctness of option (b),
What comes next?
(a) 
(b) 
(c) 
(d) 
(e) None of these
Answer (a)
Explanation: Option (a) is correct because in the given series, '6' is divided by 2, 3, 4 and 5, respectively.
Rest of the options is incorrect because of the correctness of option (a),
Counting a Particular Number
In such problems, a candidate is said to count a particular number in the series as per a given condition. For example, in the series '1 2 4 3 2 4 5 2 4', you can be asked to count 4 coming just before 3.
Commonly Asked Questions
How many 2s come just after 3 in the given series?
5 1 3 4 2 3 2 4 8 4 3 2 2 2
(a) 5 (b) 2
(c) 4 (d) 1
(e) None of these
Answer (b)
Explanation: Option (b) is correct. Just see the reason below:
2s coming just after 3 are encircled.
Rest of the options is incorrect because of the correctness of option (b).
How many 5s come just before 8 in the series given below?
8 5 7 8 5 8 5 5 8 5 8 8 7 5
(a) 4 (b) 5
(c) 1 (d) 3
(e) None of these
Answer: (d)
Explanation: Option (d) is correct. Just see the reason below:
5s coming just before 8 are encircled.
Rest of the options is incorrect because of the correctness of option (d),
Miscellaneous Problems
Such problems do not have any fixed pattern like addition, substraction, multiplication, division and number counting. Such series come before you as a surprise.
Example 1
21, 12, 30, 03,
Series pattern: The addition of both digits of every number is 3. Let us see:
Example 2
11, 21, 31, 81.
Series pattern: The last digit of every number is 1.
Commonly Asked Questions
Find the missing number in the series given below.
15, 25, 5,__,05, 65.
(a) 2 (b) 5
(c) 4 (d) 3
(e) None of these
Answer (b)
Explanation: Option (b) incorrect because the last digit in every number is 5.
Rest of the options is incorrect because of the correctness of option (b).
What can be fit in the blank space?
10, 16, 11…….18.
(a) 20 (b) 25
(c) 21 (d) 15
(e) None of these
Answer (d)
Explanation: Option (d) is correct because each number in the given series starts with 1. Rest of the options is incorrect because of the correctness of option (d).
Commonly Asked Questions
Find the missing number.
15, 20, 30, 50, __.
(a) 100 (b) 80
(c) 70 (d) 90
(e) None of these
Answer (d)
Explanation: Option (d) is correct because the series has following pattern:
Therefore, missing number will be 
Rest of the options is incorrect because of the correctness of option (d).
Fill the blank circle.
(a) 14 (b) 23
(c) 21 (d) 13
(e) None of these
Answer (d)
Explanation: Option (d) is correct because digits sum of every number is 4. Let us se
Rest of the options is incorrect because of the correctness of option (d).
What comes next in the series given in the box?
79, 87,_, 89, 83, 91.
(a) 82 (b) 81
(c) 48 (d) 62
(e) None of these
Answer (b)
Option (b) is correct because the series pattern goes as following;
Rest of the options is incorrect because of the correctness of option (b).
See the following series carefully and fill the blank space,
(a) 
(b) 
(c) (d) 
(e) None of these
Answer: (b)
Explanation: Option (b) is correct because in the given series, 4 is divided by 6 7 8 and 9, respectively. Hence, after division by 8, number 4 will definitely be divided by 9.
Rest of the options is incorrect because of the correctness of option (b).
Fill in the blanks in the given series.
1, 1, …….. 3, 5, 5, 8, …… 2, 2.
(a) 3, 8 (b) 4, 3
(c) 3, 4 (d) 5, 3
(e) None of these
Answer (a)
Explanation: Option (a) is correct because in the given series/ the numbers are in pairs and the series will be written as following.
Rest of the options is incorrect because of the correctness of option (a).
Summary
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