Number Series Questions for SSC CGL: The Short Answer
A number series question gives five or six numbers that follow a rule and asks for the missing or next term. Start with the differences between terms; if they do not settle into a pattern, test squares and cubes, primes, multiplication with addition (× n + n), and two alternating series. Those five checks solve almost every SSC series.
Key takeaway for SSC: Write the differences under the series before trying anything clever. A constant, rising or repeating difference shows the rule within seconds; a fast-growing series means multiplication is involved. Every series on this page was generated and checked with a program.
Number series appear in the reasoning sections of SSC CGL, SSC CHSL, SSC MTS, SSC GD and SSC CPO. For letter-based series, see letter series questions for SSC.
Common Number Series Patterns in SSC Exams
| Pattern | Example | Rule |
|---|---|---|
| Rising differences | 7, 9, 13, 19, 27, 37 | differences 2, 4, 6, 8, 10 |
| Squares + 3 | 28, 39, 52, 67, 84, 103 | 5² + 3, 6² + 3, ... 10² + 3 |
| Cubes + 2 | 10, 29, 66, 127, 218, 345 | 2³ + 2, 3³ + 2, ... 7³ + 2 |
| Twice the primes | 82, 86, 94, 106, 118, 122 | 2 × 41, 2 × 43, 2 × 47, ... |
| × n + n | 11, 12, 26, 81, 328, 1645 | × 1 + 1, × 2 + 2, × 3 + 3, ... |
| Alternating series | 8, 41, 13, 46, 18, 51, 23 | 8, 13, 18, 23 (+5) and 41, 46, 51 (+5) |
| Sum of previous two | 5, 9, 14, 23, 37, 60 | 5 + 9 = 14, 9 + 14 = 23, ... |
| Mixed × and + | 7, 14, 17, 34, 37, 74 | × 2, + 3, × 2, + 3, ... |
| Geometric | 3, 12, 48, 192, 768 | × 4 each time |
Number Series Solved Examples
Example 1: Difference method
7, 9, 13, 19, 27, ?
Differences: 2, 4, 6, 8, so the next difference is 10. Answer: 27 + 10 = 37.
Example 2: Missing term in × n + n
11, 12, ?, 81, 328, 1645
12 × 2 + 2 = 26, then 26 × 3 + 3 = 81, 81 × 4 + 4 = 328 and 328 × 5 + 5 = 1645. Answer: 26.
Example 3: Twice the primes
82, 86, 94, 106, 118, ?
Halve each term: 41, 43, 47, 53, 59, which are consecutive primes. The next prime is 61. Answer: 2 × 61 = 122.
Example 4: Alternating series
8, 41, 13, 46, 18, 51, ?
Odd places: 8, 13, 18 (+5). Even places: 41, 46, 51 (+5). The 7th term belongs to the first series. Answer: 23.
Example 5: Mixed operations
7, 14, 17, 34, 37, ?
Steps alternate × 2 and + 3: 7 × 2 = 14, 14 + 3 = 17, 17 × 2 = 34, 34 + 3 = 37. Answer: 37 × 2 = 74.
How to Solve Number Series Fast (Step-by-Step)
- Check growth. Slow, steady growth means addition; fast growth means multiplication or powers.
- Write the differences. Look for constant, rising, or repeating differences.
- Check squares and cubes near each term (± 1 or ± 2 is common).
- Split into odd and even places if the series jumps up and down.
- Test × n + n and × n − n when each term is roughly a multiple of the previous one.
- Confirm with the term after the gap before marking the answer.
Squares, Cubes and Primes to Remember
| Squares | 1, 4, 9, 16, 25, 36, 49, 64, 81, 100, 121, 144, 169, 196, 225 |
|---|---|
| Cubes | 1, 8, 27, 64, 125, 216, 343, 512, 729, 1000 |
| Primes below 50 | 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47 |
Common Mistakes in Number Series Questions
- Trying multiplication before checking the simple differences.
- Missing an alternating series because the terms rise and fall.
- Using the wrong power (n² vs n³) after spotting "near squares".
- Not checking the answer against the term after the question mark.
Number Series Practice Questions with Answers
- 9, 14, 21, 30, 41, ? Answer: 54. Differences 5, 7, 9, 11, 13.
- 6, 25, 62, 123, 214, ? Answer: 341. n³ − 2 for n = 2 to 7.
- 10, 9, 16, 45, 176, ? Answer: 875. × 1 − 1, × 2 − 2, × 3 − 3, × 4 − 4, × 5 − 5.
- 6, 21, 11, 26, 16, 31, ? Answer: 21. Two series: 6, 11, 16, 21 and 21, 26, 31.
- 62, 74, 82, 86, 94, ? Answer: 106. Twice the primes 31, 37, 41, 43, 47, 53.
For timed practice, take the SSC GD Number Series Mock Test 03 and the SSC MTS Number Series Mock Test 03.
Number Series FAQs
What is the first step in a number series question?
Write the differences between consecutive terms. Most SSC series show their rule in the differences or in the second differences.
How do I spot an alternating number series?
If the terms rise and fall, or jump unevenly, split them into odd and even places and check each part separately.
Which number series patterns are most common in SSC exams?
Rising differences, squares and cubes with a small adjustment, primes, × n + n, alternating series and sum-of-previous-terms series.
Practice Next
- Topic tests: SSC GD Number Series Mock Test 03, SSC MTS Number Series Mock Test 03, SSC CGL Number Series Mock Test 06 and SSC CHSL Series Mock Test 02.
- Related notes: letter series questions for SSC, missing number series tricks for bank exams and square root and cube root tricks for SSC.
- Browse all study notes.