Number Series Interview Questions and Answers
Question - 1 : - Find the missing number in the series?
4, 18, ?, 100, 180, 294, 448
A) 48 B) 50
C) 58 D) 60
Answer - 1 : -
A) 48
Explanation:
Take a Look at this series :
2^{3} - 2^{2} = 8 - 4 = 4
3^{3} - 3^{2} = 27 - 9 = 18
4^{3} - 4^{2} = 64 - 16 = 48
5^{3} - 5^{2} = 125 - 25 = 100
6^{3} - 6^{2} = 216 - 36 = 180
7^{3} - 7^{2} = 343 - 49 = 294
8^{3} - 8^{2} = 512 - 64 = 448
Question - 2 : - Find the wrong number in the series.
1, 2, 6, 15, 31, 56, 91
A) 31 B) 15
C) 56 D) 91
Answer - 2 : -
D) 91
Explanation:
The difference of the two consecutive numbers are 1, 4, 9, 16, 25, 35.
This is clearly , +(1^{2}), +(2^{2}), +(3^{2}), +(4^{2}), +(5^{2}),+(6^{2})
Here 35 is wrong, So our wrong number is 91
Question - 3 : - Find the missing number in the following series?
3, 5, 5, 19, 7, 41, 9, ?
A) 71 B) 61
C) 79 D) 69
Answer - 3 : -
A) 71
Explanation:
Fiest series : 3, 5, 7, 9
Second series : 5, 19, 41, ?
Difference of Second series are 14, 22, 30 etc
Next term is 41+30 i.e equal to 71
Question - 4 : - What should come in place of question mark (?) in the following number series?
132 156 ? 210 240 272
A) 196 B) 182
C) 199 D) 204
Answer - 4 : -
B) 182
Explanation:
The given series follows a logic that
11 x 12, 12 x 13, 13 x 14, 14 x 15, 15 x 16,...
So the missing number is 13 x 14 = 182
Question - 5 : - Find the wrong number in the given series.
8, 27, 125, 343, 1381
A) 27 B) 8
C) 343 D) 1381
Answer - 5 : -
D) 1381
Explanation:
Given series follows Cubes on Prime Numbers
i.e 2^{3}, 3^{3}, 5^{3},...but 9^{3}is 1331
so 1381 is wrong
Question - 6 : - Look at this series: 2, 1, (1/2), (1/4), ... What number should come next?
A. (1/3)
B. (1/8)
C. (2/8)
D. (1/16)
Answer - 6 : -
B
Explanation:
This is a simple division series; each number is one-half of the previous number.
In other terms to say, the number is divided by 2 successively to get the next result.
4/2 = 2
2/2 = 1
1/2 = 1/2
(1/2)/2 = 1/4
(1/4)/2 = 1/8 and so on.
Question - 7 : - Look at this series: 7, 10, 8, 11, 9, 12, ... What number should come next?
A. 7
B. 10
C. 12
D. 13
Answer - 7 : -
B
Explanation:
This is a simple alternating addition and subtraction series. In the first pattern, 3 is added; in the second, 2 is subtracted.
Question - 8 : - Look at this series: 36, 34, 30, 28, 24, ... What number should come next?
A. 20
B. 22
C. 23
D. 26
Answer - 8 : -
B
Explanation:
This is an alternating number subtraction series. First, 2 is subtracted, then 4, then 2, and so on.
Question - 9 : - Look at this series: 22, 21, 23, 22, 24, 23, ... What number should come next?
A. 22
B. 24
C. 25
D. 26
Answer - 9 : -
C) 25
Explanation:
In this simple alternating subtraction and addition series; 1 is subtracted, then 2 is added, and so on.
Question - 10 : - Look at this series: 53, 53, 40, 40, 27, 27, ... What number should come next?
A. 12
B. 14
C. 27
D. 53
Answer - 10 : -
B) 14
Explanation:
In this series, each number is repeated, then 13 is subtracted to arrive at the next number.