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
Explanation: 156 + 14 = 170
170 + 14 + 8 = 192
192 + 22 + 12 = 226
226 + 34 + 20 = 280
280 + 54 + 32 = 366
Directions(Q.16-20): In each of the following questions a number series is given. After theseries, a number is given followed by (a), (b), (c), (d) and (e). You have to complete theseries starting with the number given, following the sequence of the original series and answer the questions that follow the series.
16. 3 732 1244 1587 1803 1928
5 (a) (b) (c) (d) (e)
What will come in place of (d)?
Ans: 1805
Explanation: The difference between the numbers are perfect cubes ... required number in (d) position is 1805
17. 16 4 2 1.5 1.5 1.875
4 (a) (b) (c) (d) (e)
What will come in place of (b)?
Ans: 0.5
Explanation: 16 × 0.25 = 4
4 × 0.5 = 2
2 × 0.75 = 1.5
1.5 × 1 = 1.5
1.5 × 1.25 = 1.875
Required number is
4 × 0.25 = 1
1 × 0.5 = 0.5
18. 3 19 99 499 2499 12499
2 (a) (b) (c) (d) (e)
What will come in place of (c)?
Ans: 374
Explanation: 3 × 5 + 4 = 19
19 × 5 + 4 = 99
99 × 5 + 4 = 499
499 × 5 + 4 = 2499
2499 × 5 + 4 = 12499
Required number is
2 × 5 + 4 = 14
14 × 5 + 4 = 74
74 × 5 + 4 = 374
19. 14 19 12 23 10 27
11 (a) (b) (c) (d) (e)
What will come in place of (b)?
Ans: 9
Explanation: 14 + 5 = 19
19 − 7 = 12
12 + 11 = 23
23 − 13 = 10
10 + 17 = 27
Required number is
11 + 5 = 16
16 − 7 = 9
Short cut: Vertical difference is always constant
20. 24 144 180 900 925 3700
17 (a) (b) (c) (d) (e)
What will come in place of (e)?
Ans: 2860
Explanation: 24 × 6 = 144
144 + 62 = 180
180 × 5 = 900
900 + 52 = 925
925 × 4 = 3700
Required number is
17 × 6 = 102
102 + 36 = 138
138 × 5 = 690
690 + 25 = 715
715 × 4 = 2860
Directions (Q.21-25): In each of the following questions, a number is wrong. You have to identify that number.
21. 7.2 32 156 776 3876 19276
Ans: 19276
Explanation: 7.2 × 5 − 4 = 32
32 × 5 − 4 = 156
156 × 5 − 4 = 776
776 × 5 − 4 = 3876
3876 × 5 − 4 = 19376
22. 328 340 360 412 508 700
Ans: 360
Explanation: 328 + 12 = 340
340 + 24 = 364
364 + 48 = 412
412 + 96 = 508
508 + 192 = 700
23. 12 18 45 156.5 708.75 3898.125
Ans: 156.5
Explanation: 12 × 1.5 = 18
18 × 2.5 = 45
45 × 3.5 = 157.5
157.5 × 4.5 = 708.75
708.75 × 5.5 = 3898.125
24. 0.7 1.1 1.9 3.1 4.7 6.9
Ans: 6.9
Explanation: 0.7 + 0.4 = 1.1
1.1 + 0.8 = 1.9
1.9 + 1.2 = 3.1
3.1 + 1.6 = 4.7
4.7 + 2 = 6.7
25. 3399 1131 375 125 39 11
Ans: 125
Explanation: 3399 ÷ 3 − 2 = 1131
1131 ÷ 3 − 2 = 375
375 ÷ 3 − 2 = 123
123 ÷ 3 − 2 = 39
39 ÷ 3 − 2 = 11