Important Number Series for IBPS PO Mains: Part 8

Directions (1-5) : What value should come in place of question-mark (?) in the following number series?

Ques 1.

399, 357, 315 , 273 , 231, ?

1. 189
2. 285
3. 169
4. 2655. 245

1. 1;

The series is 20² - 1, 19² - 4, 18² - 9

17² - 16, 16² - 25, 15² - 36

∴ ? = 15² - 36 = 189

Ques 2.

165, 162, 153, 149, 133, ?
1. 138
2. 132
3. 136
4. 128
5. 140

2. 4; 

The series is

∴  ? = 133 - 5 = 128

Ques 3.

78, 117, 234, 585, 1755, ?
1. 6142.5
2. 6042.5
3. 6002.8
4. 6024.5
5. 6442.5

3. 1;

The series is 

∴ ? = 1755 x 3.5 = 6142. 5

Ques 4.

29, 60, 32, 66, ?, 72
1. 50
2. 42
3. 38
4. 48
5. 35

4. 5;

The series is 

? = 66 ÷  2+ 2 = 35

Ques 5.

39, 53, 81, 137, ?, 473
1. 246
2. 249
3. 248
4. 258
5. 259

5. 2; 

The series is 

∴ ? = 137 + 112 = 249

Ques 6.

129, 138, 163, 212, ?
1. 253
2. 293
3. 283
4. 296
5. 264

6. 2;

The series is 

i.e,

∴ ? = 212+9² = 293

Ques 7.

7, 73, 721, 5761, ?
1. 34165
2. 36451
3. 35461
4. 34651
5. 34561

7. 5;

The series is 

i.e.,

∴ ? = 5161 + 6-5 = 34561

Ques 8.

8836, 9025, 9216, 9409, ?
1. 4098
2. 9804
3. 9604
4. 9704
5. 9714

8. 3; 

The series is 94² = 8836, 95² = 9025, 96²= 9216, 97² = 9409........

∴ ? = 98² = 9604

Ques 9.

18, 66, 258, 1026, ?
1. 4098
2. 4198
3. 4089
4. 4192
5. 4088

9. 1;

The series is 

∴ ? = 1026 x 4 - 6 = 4098

Ques 10.

340, 732, 1328, 2200, ?
1. 3382
2. 3273
3. 3732
4. 3372
5. 3237

10. 4;

The series is :7³ - 3 = 340, 9³ + 3 = 732 ,

11³ - 3 = 1328 , 13³ + 3 = 2200

∴ ? = 15³ - 3 = 3372