Number Series Quiz For IBPS PO Part- 10

Direction (Q.1-10): What should come at the place of question mark (?) in the following number series? 

Q.1  221, 109, 53, 25, 11, ?

A. 6
B. 4
C. 8
D. 10
E. 15
Ans. B.
Explanation: 
(221-3)÷2 = 109
(109-3)÷2 = 53
(53-3)÷2 = 25
(25-3)÷2 = 11
(11-3)÷2 = 4

Q.2  0.5, 12, 52, 106, 107, ?

A. 40
B. 45
C. 50
D. 54
E. None of these
Ans. D.
Explanation: 
0.5×8+8 = 12
12×4+4 = 52
52×2+2 = 106
106×1+1 = 107
107×.5+.5 = 54

Q.3  39, 31, 41, 29, 43, ?

A. 20
B. 25
C. 27
D. 30
E. 29
Ans. C.
Explanation: 
This is the mixture of 2 series:
39+2 = 41
41+2 = 43
31-2 = 29
29-2 = 27

Q.4  3, 5, 13, 49, ? , 1441

A. 300
B. 295
C. 325
D. 245
E. 241
Ans. E.
Explanation: 
3×2-1 = 5
5×3-2 = 13
13×4-3 = 49
49×5-4 = 241
242×6-5 = 1441

Q.5  481, 477, 467, 439, 357, ?

A. 110
B. 113
C. 115
D. 120
E. 125
Ans. B.
Explanation: 

Q.6  17, 31, 15, 33, 13, ?

A. 39
B. 37
C. 30
D. 35
E. None of these
Ans. D.
Explanation: 
This is the mixture of 2 series:
17-2 = 15
15-2 = 13
31+2 = 33
33+2 = 35

Q.7  0.5, 2, 8, 35, ?, 1079

A. 160
B. 179
C. 185
D. 175
E. 182
Ans. B.
Explanation: 
0.5×2+1 = 2
2×3+2 = 8
8×4+3 = 35
35×5+4 = 179
179×6+5 = 1079

Q.8  167, 164, 159, 150, ?, 100

A. 129
B. 122
C. 130
D. 125
E. 133
Ans. E.
Explanation: 

Q.9  2, 8, 28, 54, 53, ?

A. 26
B. 24
C. 28
D. 30
E. 25
Ans. A.
Explanation: 
2×8-8 = 8
8×4-4 = 28
28×2-2 = 54
54×1-1 = 53
53×.5-.5 = 26

Q.10  973, 325, 109, 37, 13, ?

A. 9
B. 3
C. 5
D. 8
E. 10
Ans. C.
Explanation:
973+2÷3 = 325
325+2÷3 = 109
109+2÷3 = 37
37+2÷3 = 13
13+2÷3 = 5