# Aptitude Questions: Number Series Set 39

Hello Aspirants. Welcome to Online Quantitative Aptitude Section in AffairsCloud.com. Here we are creating question sample in Number Series, which is common for all the competitive exams. We have included Some questions that are repeatedly asked in bank exams !!!

Directions(1-10) : In these questions, a number series is given. Find out the missing number.

1. 18 10 8 9 11.5 ?
A. 14.75
B. 10.75
C. 18.75
D. 19.75
E. 20.75
Explanation :
18 / 2 + 1 = 10
10 / 2 + 3 = 8
8 / 2 + 5 = 9

2. 6 4 6 12 22 ?
A. 26
B. 36
C. 86
D. 66
E. 46
Explanation :
6 / 2 + 1² = 4
4 / 2 + 2² = 6
6 / 2 + 3² = 12….

3. 20 39 74 ? 262 499
A. 146
B. 169
C. 166
D. 139
E. 129
Explanation :
20*2 – 1² = 39
39*2 – 2² = 74
74*2 – 3² = 139…..

4. 15 32 60 122 240 ?
A. 362
B. 488
C. 482
D. 364
E. 382
Explanation :
15 * 2 + 2 = 32
32 * 2 – 4 = 60
60 * 2 + 2 = 122; 122 * 2 – 4 = 240…

5. 14 12 28 78 320 ?
A. 1450
B. 1590
C. 1440
D. 1810
E. 1690
Explanation :
14 * 1 – 2 = 12
12 * 2 + 4 = 28
28 * 3 – 6 = 78; 78 * 4 + 8 = 320; 320 * 5 – 10 = 1590

6. 31, 16, 10, 13, 38.5, ?
A. 167.25
B. 177.25
C. 147.25
D. 174.25
E. 185.25
Explanation :
31 / 2 + 0.5 = 16
16 / 2 + 2 = 10
10 / 2 + 8 = 13
13 / 2 + 32 = 38.5…..

7. 25 25 37 57 113 ?
A. 202
B. 207
C. 185
D. 195
E. 190
Explanation :
25 + 1² – 1 = 25
25 + 3² + 3 = 37
37 + 5² – 5 = 57…..

8. 18, 20, 40, 70, 142 ?
A. 232
B. 254
C. 188
D. 196
E. 240
Explanation :
18 + 2² – 2 = 20; 20 + 4²+ 4 = 40; 40 + 6² – 6 = 70 ….

9. 720 520 336 222 120 ?
A. 78
B. 68
C. 76
D. 56
E. 58
Explanation :
9³ – 9 = 720
8³ + 8 = 520
7³ – 7 = 336
6³ + 6 = 222….

10. 72, 72, 42, 42, 20, ?
A. 30
B. 40
C. 50
D. 20
E. 10