Quantitative Aptitude

Number Series questions with solutions

Number series is common to bank, SSC and railway papers. Bank exams ask for the next or missing term in a set of five; SSC and RRB mix it into reasoning. The same few patterns repeat, so recognising them quickly is the whole skill.

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Prepared by the CBTAdda content team · Updated 28 October 2026 · How we check our content

How to solve number series questions

Write the differences between consecutive terms. If they form a pattern (constant, increasing by a fixed amount, squares, cubes), you have found the rule.
If differences grow very fast, test multiplication: ×2, ×3, or × 1, 2, 3, 4… often with a small addition (×2 + 1).
If the terms go up and down, check for two alternating operations or two interleaved series.

Common trap: Check your rule against every term, not just the first three. Distractor options are built from rules that fit only the start.

12 practice questions

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Find the next term: 3, 10, 29, 66, 127, 218, ?
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Answer: (C) 345. The terms are n³ + 2 for n = 1 to 6. Next: 7³ + 2 = 345.
Find the next term: 58, 62, 72, 88, 110, 138, ?
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Answer: (C) 172. The differences increase by 6 each time (4, 10, 16, 22, 28), so the next difference is 34. 138 + 34 = 172.
Find the next term: 9, 28, 65, 126, 217, 344, ?
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Answer: (D) 513. The terms are n³ + 1 for n = 2 to 7. Next: 8³ + 1 = 513.
Find the next term: 14, 17, 16, 19, 18, 21, ?
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Answer: (D) 24. The series alternates between +3 and −1. The next step is +3: 21 + 3 = 24.
Find the next term: 28, 65, 126, 217, 344, 513, ?
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Answer: (A) 730. The terms are n³ + 1 for n = 3 to 8. Next: 9³ + 1 = 730.
Find the next term: 5, 5, 10, 30, 120, 600, ?
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Answer: (D) 3600. Multiply by 1, 2, 3, 4, 5 in turn, so the next step is × 6. 600 × 6 = 3600.
Find the next term: 40, 41, 45, 54, 70, 95, ?
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Answer: (A) 131. The differences are 1², 2², 3², 4², 5², so the next difference is 6² = 36. 95 + 36 = 131.
Find the next term: 9, 30, 93, 282, 849, 2550, ?
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Answer: (A) 7653. Each term is (previous × 3) + 3. 2550 × 3 + 3 = 7653.
Find the next term: 32, 33, 37, 46, 62, 87, ?
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Answer: (B) 123. The differences are 1², 2², 3², 4², 5², so the next difference is 6² = 36. 87 + 36 = 123.
Find the next term: 18, 27, 23, 32, 28, 37, ?
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Answer: (B) 46. The series alternates between +9 and −4. The next step is +9: 37 + 9 = 46.
Find the next term: 26, 29, 35, 44, 56, 71, ?
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Answer: (A) 89. The differences increase by 3 each time (3, 6, 9, 12, 15), so the next difference is 18. 71 + 18 = 89.
Find the next term: 61, 122, 213, 340, 509, 726, ?
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Answer: (D) 997. The terms are n³ − 3 for n = 4 to 9. Next: 10³ − 3 = 997.