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15 Number Series Questions and Answers

15 solved Number Series questions with step-by-step explanations. Includes formulas, shortcuts, and tips for placement tests and competitive exams.

Number series questions test your ability to identify patterns and predict the next term in a sequence. These are common in logical reasoning sections of placement and competitive exams. The patterns can be arithmetic (+2, +5, -3), geometric (×2, ÷3), or more complex involving alternating operations, squares, cubes, or combinations. A systematic approach — checking differences between consecutive terms, then ratios, then higher-order patterns — is the most reliable method. Below are solved number series questions with explanations to sharpen your pattern recognition skills.

Q1 Easy

Find the next number: 5, 30, 14, 26, 14, 30, ?

  • A. 12
  • B. 16
  • C. 14
  • D. 18
Explanation: Odd positions follow +2 sequence. Next odd-position term is 16.
Q2 Easy

Find the next number: 3, 7, 11, 15, 19, ?

  • A. 25
  • B. 21
  • C. 23
  • D. 20
Explanation: Arithmetic progression with common difference 4. Next = 23.
Q3 Easy

Find the next number: 11, 20, 15, 27, 12, 34, ?

  • A. 10
  • B. 16
  • C. 12
  • D. 14
Explanation: Odd positions follow +2 sequence. Next odd-position term is 14.
Q4 Easy

Find the next number: 14, 21, 28, 35, 42, ?

  • A. 51
  • B. 47
  • C. 46
  • D. 49
Explanation: Arithmetic progression with common difference 7. Next = 49.
Q5 Easy

Find the next number: 9, 24, 7, 35, 14, 35, ?

  • A. 18
  • B. 14
  • C. 16
  • D. 12
Explanation: Odd positions follow +2 sequence. Next odd-position term is 16.
Q6 Easy

Find the next number: 11, 15, 19, 23, 27, ?

  • A. 31
  • B. 28
  • C. 33
  • D. 29
Explanation: Arithmetic progression with common difference 4. Next = 31.
Q7 Medium

Find the next number: 10, 25, 7, 23, 14, 26, ?

  • A. 14
  • B. 18
  • C. 12
  • D. 16
Explanation: Odd positions follow +2 sequence. Next odd-position term is 16.
Q8 Medium

Find the next number in the pattern: 4, 8, 16, 32, 64, ?

  • A. 133
  • B. 118
  • C. 123
  • D. 128
Explanation: Geometric progression with ratio 2. Next = 64 x 2 = 128.
Q9 Medium

Find the next number: 6, 23, 17, 29, 19, 37, ?

  • A. 23
  • B. 17
  • C. 19
  • D. 21
Explanation: Odd positions follow +2 sequence. Next odd-position term is 21.
Q10 Medium

Find the next number in the pattern: 2, 4, 8, 16, 32, ?

  • A. 69
  • B. 54
  • C. 64
  • D. 59
Explanation: Geometric progression with ratio 2. Next = 32 x 2 = 64.
Q11 Medium

Find the next number: 11, 21, 14, 34, 17, 34, ?

  • A. 19
  • B. 15
  • C. 21
  • D. 17
Explanation: Odd positions follow +2 sequence. Next odd-position term is 19.
Q12 Hard

Find the next number in the pattern: 4, 12, 36, 108, 324, ?

  • A. 962
  • B. 972
  • C. 967
  • D. 977
Explanation: Geometric progression with ratio 3. Next = 324 x 3 = 972.
Q13 Hard

Find the next number: 9, 23, 9, 27, 12, 35, ?

  • A. 14
  • B. 16
  • C. 10
  • D. 12
Explanation: Odd positions follow +2 sequence. Next odd-position term is 14.
Q14 Hard

Find the next number in the pattern: 5, 15, 45, 135, 405, ?

  • A. 1215
  • B. 1205
  • C. 1210
  • D. 1220
Explanation: Geometric progression with ratio 3. Next = 405 x 3 = 1215.
Q15 Hard

Find the next number: 5, 20, 17, 29, 9, 31, ?

  • A. 9
  • B. 7
  • C. 13
  • D. 11
Explanation: Odd positions follow +2 sequence. Next odd-position term is 11.

Key Takeaways

  • Always check differences first — they reveal the underlying pattern.
  • If differences don't help, check ratios between consecutive terms.
  • Look for alternating patterns, square/cube sequences, or combined rules.
  • Practice is key: the more patterns you see, the faster you recognize them.

Frequently Asked Questions

How do I solve number series questions?

First check the difference between consecutive terms. If differences form a pattern (constant, increasing, or themselves a series), that reveals the rule. If not, check ratios. If neither works, look for alternating patterns, squares, cubes, or combination rules.

What are common number series patterns?

Arithmetic (+/- constant), Geometric (×/÷ constant), Square/Cube patterns, Fibonacci-like (sum of previous two), Alternating (two interleaved series), and Mixed (combination of arithmetic and geometric).

More Number Series Practice Resources

For more number series practice, try our timed quiz mode that generates fresh questions every session.