Wrong Number Series Tricks for Bank Exams
A wrong-number series is a normal series with one term changed. Find the rule from the terms that agree with each other, then recompute every term.
Method
- Use the first three or four terms to guess the rule, then confirm it on the rest.
- Recompute every term from its neighbour; the one that doesn’t match is the wrong number.
- The wrong term breaks two steps — the step into it and the step out of it. If only the last step breaks, the last term is wrong.
- If your rule fails in two separate places, the rule is wrong, not the series. Try the next pattern.
Worked examples
- 2, 5, 14, 41, 125, 365 → rule × 3 − 1: 2 → 5 → 14 → 41 → 122 → 365. 125 should be 122.
- 16, 4, 8, 2, 6, 1 → rule ÷ 4, × 2 alternating: 16 → 4 → 8 → 2 → 4 → 1. 6 should be 4.
- 256, 400, 576, 788, 1024 → squares of 16, 20, 24, 28, 32. 788 should be 784 (28²).
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
More shortcuts and tables
Looking for the exam itself? See the exam patterns for SBI, IBPS and RRB.