Practice Number Series with this set of 60 questions. These questions are useful for Aptitude and Reasoning exams. You will see common numerical and arithmetic series patterns. Try each question first, then check the answers and solutions. It’s a simple way to improve speed and accuracy in series questions.
For more aptitude questions across different chapters, jump here: aptitude question and answers.
Number Series Patterns and Shortcuts
Difference series
Equal difference, an AP: 3, 7, 11, 15, 19 with a difference of 4
Increasing difference: 2, 3, 5, 8, 12 where the differences are 1, 2, 3, 4
Difference in an AP or GP of its own: 1, 3, 8, 18, 35 where the differences are 2, 5, 10, 17
Ratio series
Fixed ratio, a GP: 3, 6, 12, 24, 48 with a ratio of 2
Changing ratio: 2, 4, 12, 48, 240 where the multipliers are 2, 3, 4, 5
Multiply and add: 3, 7, 15, 31, 63 where each term is the previous one doubled plus 1
Square based series
Plain squares: 1, 4, 9, 16, 25
Squares with an adjustment: 2, 5, 10, 17, 26 which is n² + 1
Squares of odd or even numbers only: 1, 9, 25, 49 or 4, 16, 36, 64
Squares till 30 must be on your fingertips: 1, 4, 9, 16, 25, 36, 49, 64, 81, 100, 121, 144, 169, 196, 225, 256, 289, 324, 361, 400, 441, 484, 529, 576, 625, 676, 729, 784, 841, 900
Cube based series
Plain cubes: 1, 8, 27, 64, 125
Cubes with an adjustment: 2, 9, 28, 65, 126 which is n³ + 1
Cubes till 20: 1, 8, 27, 64, 125, 216, 343, 512, 729, 1000, 1331, 1728, 2197, 2744, 3375, 4096, 4913, 5832, 6859, 8000
Prime based series
Plain primes: 2, 3, 5, 7, 11, 13, 17, 19, 23
Primes with an adjustment: 4, 6, 8, 10, 14 which is prime plus 1
There are 25 primes below 100. Learn them once and you will spot these instantly.
Alternating or mixed series
Two series woven together: 2, 5, 8, 11, 14, 17 read at odd places gives 2, 8, 14 and at even places gives 5, 11, 17
The giveaway is that the numbers rise and fall, or the differences make no sense at all. Split it and both halves become obvious.
The other patterns worth knowing
Fibonacci type, where each term is the sum of the two before it: 1, 1, 2, 3, 5, 8, 13
Each term is the sum of the two before it plus a number: 2, 3, 6, 11, 20
Multiply by a fraction: 64, 32, 16, 8 or 3, 4.5, 6.75 where the multiplier is 1.5
Add the digits of the previous term: 12, 15, 21, 24, 30
Number Series Questions with Solutions (Aptitude + Reasoning Series Test)
Arithmetic / Difference Series: 20 MCQ Questions
Question 1. Find the next number in the series: 5, 9, 13, 17, ___
a) 19
b) 21
c) 23
d) 25
Answer:
b) 21
Question 2. Find the next number in the series: 40, 37, 34, 31, ___
a) 30
b) 28
c) 27
d) 26
Answer:
b) 28
Question 3. Find the next number in the series: 3, 8, 13, 18, ___
a) 21
b) 22
c) 23
d) 24
Answer:
c) 23
Question 4. Find the next number in the series: 100, 93, 86, 79, ___
a) 74
b) 73
c) 72
d) 71
Answer:
b) 72
Question 5. Find the next number in the series: 2, 5, 9, 14, 20, ___
a) 25
b) 26
c) 27
d) 28
Answer:
c) 27
Question 6. Find the next number in the series: 1, 4, 9, 16, 25, ___
a) 30
b) 32
c) 34
d) 36
Answer:
d) 36
Question 7. Find the next number in the series: 12, 15, 19, 24, 30, ___
a) 35
b) 36
c) 37
d) 38
Answer:
c) 37
Question 8. Find the next number in the series: 50, 47, 43, 38, 32, ___
a) 26
b) 27
c) 28
d) 29
Answer:
a) 26
Question 9. Find the next number in the series: 7, 14, 12, 19, 17, ___
a) 22
b) 24
c) 25
d) 26
Answer:
b) 24
Question 10. Find the next number in the series: 2, 6, 4, 8, 6, 10, ___
a) 6
b) 7
c) 8
d) 9
Answer:
c) 8
Question 11. Find the next number in the series: 30, 28, 26, 23, 21, 19, ___
a) 18
b) 17
c) 16
d) 15
Answer:
c) 16
Question 12. Find the next number in the series: 4, 11, 18, 25, ___
a) 30
b) 31
c) 32
d) 33
Answer:
c) 32
Question 13. Find the next number in the series: 9, 7, 10, 8, 11, 9, ___
a) 10
b) 11
c) 12
d) 13
Answer:
c) 12
Question 14. Find the next number in the series: 1, 3, 6, 10, 15, ___
a) 18
b) 19
c) 20
d) 21
Answer:
d) 21
Question 15. Find the next number in the series: 60, 55, 49, 42, 34, ___
a) 26
b) 27
c) 28
d) 29
Answer:
a) 26
Question 16. Find the next number in the series: 8, 13, 19, 26, 34, ___
a) 41
b) 42
c) 43
d) 44
Answer:
c) 43
Question 17. Find the next number in the series: 15, 12, 16, 13, 17, 14, ___
a) 16
b) 17
c) 18
d) 19
Answer:
c) 18
Question 18. Find the next number in the series: 6, 10, 15, 21, 28, ___
a) 34
b) 35
c) 36
d) 37
Answer:
b) 35
Question 19. Find the next number in the series: 90, 81, 73, 66, 60, ___
a) 55
b) 54
c) 53
d) 52
Answer:
b) 54
Question 20. Find the next number in the series: 11, 22, 20, 31, 29, ___
a) 38
b) 39
c) 40
d) 41
Answer:
b) 39
Multiplicative / Ratio Series: 20 MCQ Questions
Question 1. Find the next number in the series: 64, 32, 16, 8, ___
a) 2
b) 3
c) 4
d) 6
Answer:
c) 4
Question 2. Find the next number in the series: 3, 6, 12, 24, ___
a) 36
b) 40
c) 44
d) 48
Answer:
d) 48
Question 3. Find the next number in the series: 5, 15, 45, 135, ___
a) 270
b) 360
c) 405
d) 540
Answer:
c) 405
Question 4. Find the next number in the series: 81, 27, 9, 3, ___
a) 1
b) 2
c) 3
d) 4
Answer:
a) 1
Question 5. Find the next number in the series: 2, 4, 12, 24, 72, ___
a) 96
b) 120
c) 144
d) 216
Answer:
d) 216
Question 6. Find the next number in the series: 1, 2, 6, 24, ___
a) 48
b) 96
c) 120
d) 144
Answer:
c) 120
Question 7. Find the next number in the series: 7, 14, 28, 56, ___
a) 84
b) 98
c) 112
d) 126
Answer:
c) 112
Question 8. Find the next number in the series: 100, 50, 25, 12.5, ___
a) 5.25
b) 6.25
c) 7.25
d) 8.25
Answer:
b) 6.25
Question 9. Find the next number in the series: 4, 12, 36, 108, ___
a) 216
b) 324
c) 432
d) 486
Answer:
c) 324
Question 10. Find the next number in the series: 9, 18, 54, 108, ___
a) 216
b) 270
c) 288
d) 324
Answer:
a) 216
Question 11. Find the next number in the series: 2, 8, 32, 128, ___
a) 256
b) 384
c) 512
d) 640
Answer:
c) 512
Question 12. Find the next number in the series: 10, 5, 20, 10, 40, ___
a) 15
b) 20
c) 25
d) 30
Answer:
b) 20
Question 13. Find the next number in the series: 6, 3, 6, 3, 6, ___
a) 1
b) 2
c) 3
d) 4
Answer:
c) 3
Question 14. Find the next number in the series: 11, 22, 44, 88, ___
a) 99
b) 132
c) 144
d) 176
Answer:
d) 176
Question 15. Find the next number in the series: 1, 3, 9, 27, ___
a) 54
b) 72
c) 81
d) 243
Answer:
d) 81
Question 16. Find the next number in the series: 16, 8, 4, 2, ___
a) 0.25
b) 0.5
c) 1
d) 1.5
Answer:
c) 1
Question 17. Find the next number in the series: 3, 9, 18, 54, 108, ___
a) 162
b) 216
c) 324
d) 432
Answer:
b) 216
Question 18. Find the next number in the series: 12, 6, 18, 9, 27, ___
a) 10
b) 11
c) 12
d) 13.5
Answer:
d) 13.5
Question 19. Find the next number in the series: 5, 10, 8, 16, 14, ___
a) 26
b) 28
c) 30
d) 32
Answer:
b) 28
Question 20. Find the next number in the series: 2, 5, 10, 17, 26, ___
a) 35
b) 36
c) 37
d) 38
Answer:
b) 37
Mixed / Structured Series (Interleaving + Alpha-numeric): 20 MCQ Questions
Question 1. Find the next number in the series: 2, 10, 4, 8, 6, 6, ___
a) 4
b) 6
c) 8
d) 10
Answer:
c) 8
Question 2. Find the next two numbers in the series: 28, 25, 5, 21, 18, 5, 14, ___, ___
a) 12, 5
b) 11, 5
c) 10, 7
d) 11, 8
Answer:
b) 11, 5
Question 3. Find the next number in the series: 1, 4, 2, 8, 3, 12, ___
a) 4
b) 14
c) 16
d) 20
Answer:
a) 4
Question 4. Find the next number in the series: 9, 1, 8, 2, 7, 3, ___
a) 4
b) 5
c) 6
d) 7
Answer:
c) 6
Question 5. Find the next number in the series: A1, B2, C4, D8, ___
a) E10
b) E12
c) E16
d) F16
Answer:
c) E16
Question 6. Find the missing term in the series: F2, ___, D8, C16, B32
a) E2
b) E4
c) E6
d) G4
Answer:
b) E4
Question 7. Find the next number in the series: 3, 6, 2, 8, 1, 10, ___
a) 0
b) 1
c) 2
d) 3
Answer:
a) 0
Question 8. Find the next number in the series: 11, 22, 12, 24, 13, 26, ___
a) 14
b) 27
c) 28
d) 29
Answer:
a) 14
Question 9. Find the next number in the series: 5, 100, 10, 50, 15, 25, ___
a) 20
b) 12.5
c) 30
d) 18
Answer:
a) 20
Question 10. Find the next number in the series: 1, 2, 1, 4, 1, 8, ___
a) 1
b) 2
c) 4
d) 16
Answer:
a) 1
Question 11. Find the next number in the series: 20, 19, 18, 16, 15, 14, ___
a) 13
b) 12
c) 11
d) 10
Answer:
b) 12
Question 12. Find the next number in the series: 2, 3, 5, 8, 12, 17, ___
a) 21
b) 22
c) 23
d) 24
Answer:
c) 23
Question 13. Find the next number in the series: 6, 1, 5, 2, 4, 3, ___
a) 3
b) 4
c) 2
d) 1
Answer:
a) 3
Question 14. Find the next number in the series: Z2, Y4, X8, W16, ___
a) V24
b) V32
c) U32
d) V64
Answer:
b) V32
Question 15. Find the next two numbers in the series: 42, 40, 38, 35, 33, 31, 28, ___, ___
a) 26, 24
b) 25, 23
c) 26, 22
d) 24, 22
Answer:
a) 26, 24
Question 16. Find the next number in the series: 2, 7, 3, 8, 4, 9, ___
a) 5
b) 6
c) 10
d) 11
Answer:
a) 5
Question 17. Find the next number in the series: 15, 3, 14, 4, 13, 5, ___
a) 12
b) 6
c) 11
d) 7
Answer:
a) 12
Question 18. Find the next number in the series: 4, 9, 5, 8, 6, 7, ___
a) 5
b) 6
c) 7
d) 4
Answer:
d) 4
Question 19. Find the next number in the series: 1, 3, 2, 6, 3, 9, 4, ___
a) 10
b) 11
c) 12
d) 13
Answer:
c) 12
Question 20. Find the missing term in the series: C3, E6, G12, I24, ___
a) J48
b) K48
c) K36
d) L48
Answer:
b) K48
Aptitude Questions and Answers for other topics
| Number system and series | ||
|---|---|---|
| HCF and LCM | Simplification | Number Series |
| Interest and commercial maths | ||
| Percentage | Profit and Loss | Compound Interest |
| Partnership | ||
| Ratio, average and mixture | ||
| Ratio and Proportion | Alligation or Mixture | Problems on Ages |
| Speed, time and distance | ||
| Time and Distance | Problems on Trains | Boats and Streams |
| Work and rate | ||
| Time and Work | Pipes and Cistern | |
| Mensuration | ||
| Volume and Surface Area | Height and Distance | |
| Permutation and probability | ||
| Permutation and Combination | Probability | |
| Calendar and clock | ||
| Calendar | Clock | |
