Directions (Q.1-5): What should come in place of question mark (?) in the following number series questions?
1. 2 1 1 1.5 3 ?
Ans: 7.5
Explanation: 2 × 0.5 = 1
1 × 1 = 1
1 × 1.5 = 1.5
1.5 × 2 = 3
3 × 2.5 = 7.5
2. 51 66 83 102 123 ?
Ans: 146
Explanation: 72 + 2 = 51
82 + 2 = 66
92 + 2 = 83
102 + 2 = 102
112 + 2 = 123
122 + 2 = 146
3. 4 24 84 264 804 ?
Ans: 2424
Explanation: 4 × 3 + 12 = 24
24 × 3 + 12 = 84
84 × 3 + 12 = 264
264 × 3 + 12 = 804
804 × 3 + 12 = 2424
4. 24 36.2 30.4 33.6 32 ?
Ans: 32.8
Explanation: 24 + 12.8 = 36.8
36.8 − 6.4 = 30.4
30.4 + 3.2 = 33.6
33.6 − 1.6 = 32
32 + 0.8 = 32.8
5. 6 9 13.5 20.25 30.375 ?
Ans: 49.7525
Explanation: 6 × 3 ÷ 2 = 9
9 × 3 ÷ 2 = 13.5
13.5 × 3 ÷ 2 = 20.25
20.25 × 3 ÷ 2 = 30.375
30.375 × 3 ÷ 2 = 45.5625
Directions (Q.6-10): In each of the following questions, a number series is given. One number is missing. What is that missing number?
6. 2 ? 19 45 99 209 431
Ans: 7
Explanation: 2 × 2 + 3 = 7
7 × 2 + 5 = 19
19 × 2 + 7 = 45
45 × 2 + 9 = 99
99 × 2 + 11 = 209
209 × 2 + 13 = 431
7. ? 4 6 12 30 90 315
Ans: 4
Explanation: 4 × 1 = 4
4 × 1.5 = 6
6 × 2 = 12
12 × 2.5 = 30
30 × 3 = 90
90 × 3.5 = 315
8. 48 62 78 96 116 ? 162
Ans: 138
Explanation: 72 − 1, 82 − 2, 92 − 3,
102 − 4, 112 − 5,
122 − 6, 132 − 7
9. 54 35 ? 3 −10 −21 −30
Ans: 18
Explanation: 54 − 19 = 35
35 − 17 = 18
18 − 15 = 3
3 − 13 = −10
−10 − 11 = −21
− 21 − 9 = −30
10. 11 12 20 43 ? 339.5 1194.25
Ans: 111.5
Explanation: 11 × 1 + 1 = 12
12 × 1.5 + 2 = 20
20 × 2 + 3 = 43
43 × 2.5 + 4 = 111.5
111.5 × 3 + 5 = 339.5
339.5 × 3.5 + 6 = 1194.25
Directions (Q.11-15): In each of the following number series questions a number is wrong. You have to identify that number.
11. 4 6 9 13.5 20 30.375
Ans: 20
Explanation: 4 × 1.5 = 6
6 × 1.5 = 9
9 × 1.5 = 13.5
13.5 × 1.5 = 20.25
20.25 × 1.5 = 30.375
12. 11 13 30 99 412 2085
Ans: 11
Explanation: 12 × 1 + 1 = 13
13 × 2 + 4 = 30
30 × 3 + 9 = 99
99 × 4 + 16 = 412
412 × 5 + 25 = 2085
13. 3 4 10 32 155 924
Ans: 10
Explanation: 3 × 2 − 2 = 4
4 × 3 − 3 = 9
9 × 4 − 4 = 32
32 × 5 − 5 = 155
155 × 6 − 6 = 924
14. 208 214 232 262 302 358
Ans: 302
Explanation: 208 + 6 = 214
214 + 18 = 232
232 + 30 = 262
262 + 42 = 304
304 + 54 = 358
15. 156 170 192 226 280 364
Ans: 364