Number Series Tricks for Bank Exams

Check in this order

• Differences: 5, 9, 15, 23, 33 → differences 4, 6, 8, 10 (step +2) → next 33 + 12 = 45.
• Second differences: if the first differences aren’t regular, take differences again.
• Multiplication: 3, 6, 12, 24 → × 2 each time. Growth that speeds up fast means × or squares.
• Changing multiplier: 2, 6, 24, 120, 720 → × 3, × 4, × 5, × 6 → next 720 × 7 = 5040.
• × n + k: 2, 5, 11, 23, 47 → × 2 + 1 → next 95.
• Division: 2187, 729, 243, 81 → ÷ 3 each time.

Special patterns

• Squares / cubes: 0, 1, 4, 9, 16, 25 → n². 1331, 729, 343, 125 → 11³, 9³, 7³, 5³ → next 3³ = 27.
• Square or cube ± k: 2, 5, 10, 17, 26 → n² + 1.
• Prime-number differences: differences 2, 3, 5, 7, 11, 13 …
• Two series mixed together: odd positions follow one rule, even positions another (1, 10, 3, 20, 5, 30 …).
• Alternating operations: × 2, + 3, × 2, + 3 …

Squares 1–30

1²

1

2²

4

3²

9

4²

16

5²

25

6²

36

7²

49

8²

64

9²

81

10²

100

11²

121

12²

144

13²

169

14²

196

15²

225

16²

256

17²

289

18²

324

19²

361

20²

400

21²

441

22²

484

23²

529

24²

576

25²

625

26²

676

27²

729

28²

784

29²

841

30²

900

Cubes 1–20

1³

1

2³

8

3³

27

4³

64

5³

125

6³

216

7³

343

8³

512

9³

729

10³

1000

11³

1331

12³

1728

13³

2197

14³

2744

15³

3375

16³

4096

17³

4913

18³

5832

19³

6859

20³

8000