Number Series Questions and Answers
Practise these 100+ number series reasoning questions to improve your ability to identify numerical patterns. The set includes addition, subtraction, multiplication, division, squares, cubes, and mixed-difference series with interactive answers and explanations.
1. Find the next number in the series:
2, 4, 6, 8, ?
Each term increases by 2, so the next term is 8 + 2 = 10.
2. Find the next number in the series:
5, 10, 15, 20, ?
Each term increases by 5, so the next term is 20 + 5 = 25.
3. Find the next number in the series:
3, 6, 9, 12, ?
Each term increases by 3, so the next term is 12 + 3 = 15.
4. Find the next number in the series:
10, 20, 30, 40, ?
The common difference is 10; 40 + 10 = 50.
5. Find the next number in the series:
7, 14, 21, 28, ?
The terms are multiples of 7. The next term is 28 + 7 = 35.
6. Find the next number in the series:
1, 3, 5, 7, ?
The series contains consecutive odd numbers. The next term is 9.
7. Find the next number in the series:
2, 5, 8, 11, ?
Each term increases by 3, so 11 + 3 = 14.
8. Find the next number in the series:
20, 18, 16, 14, ?
Each term decreases by 2, so 14 − 2 = 12.
9. Find the next number in the series:
100, 90, 80, 70, ?
The common difference is −10; 70 − 10 = 60.
10. Find the next number in the series:
4, 8, 12, 16, ?
Each term increases by 4, so 16 + 4 = 20.
11. Find the next number in the series:
1, 4, 7, 10, ?
Each term increases by 3, so 10 + 3 = 13.
12. Find the next number in the series:
9, 18, 27, 36, ?
The terms increase by 9. Therefore, 36 + 9 = 45.
13. Find the next number in the series:
50, 45, 40, 35, ?
Each term decreases by 5, so 35 − 5 = 30.
14. Find the next number in the series:
6, 12, 18, 24, ?
Each term increases by 6, so the next term is 30.
15. Find the next number in the series:
11, 22, 33, 44, ?
The terms are multiples of 11. The next term is 55.
16. Find the next number in the series:
2, 6, 10, 14, ?
Each term increases by 4, so 14 + 4 = 18.
17. Find the next number in the series:
30, 27, 24, 21, ?
Each term decreases by 3, so 21 − 3 = 18.
18. Find the next number in the series:
8, 16, 24, 32, ?
Each term increases by 8, so 32 + 8 = 40.
19. Find the next number in the series:
13, 17, 21, 25, ?
The common difference is 4; 25 + 4 = 29.
20. Find the next number in the series:
90, 80, 70, 60, ?
Each term decreases by 10, so 60 − 10 = 50.
21. Find the next number in the series:
1, 2, 4, 8, ?
Each term is multiplied by 2. Therefore, 8 × 2 = 16.
22. Find the next number in the series:
3, 6, 12, 24, ?
Each term is doubled, so 24 × 2 = 48.
23. Find the next number in the series:
5, 10, 20, 40, ?
The terms are multiplied by 2; 40 × 2 = 80.
24. Find the next number in the series:
2, 4, 8, 16, ?
Each term is doubled, so the next term is 32.
25. Find the next number in the series:
81, 27, 9, 3, ?
Each term is divided by 3; 3 ÷ 3 = 1.
26. Find the next number in the series:
64, 32, 16, 8, ?
Each term is divided by 2, so 8 ÷ 2 = 4.
27. Find the next number in the series:
256, 128, 64, 32, ?
The terms are successively divided by 2; 32 ÷ 2 = 16.
28. Find the next number in the series:
7, 14, 28, 56, ?
Each term is multiplied by 2, so 56 × 2 = 112.
29. Find the next number in the series:
4, 12, 36, 108, ?
Each term is multiplied by 3; 108 × 3 = 324.
30. Find the next number in the series:
2, 10, 50, 250, ?
Each term is multiplied by 5, so 250 × 5 = 1250.
31. Find the next number in the series:
1, 3, 9, 27, ?
Each term is multiplied by 3; 27 × 3 = 81.
32. Find the next number in the series:
1, 4, 9, 16, ?
These are squares of 1, 2, 3, and 4. The next is 5² = 25.
33. Find the next number in the series:
4, 9, 16, 25, ?
These are 2², 3², 4², and 5². The next is 6² = 36.
34. Find the next number in the series:
9, 16, 25, 36, ?
The terms are consecutive squares from 3² onward. The next is 7² = 49.
35. Find the next number in the series:
1, 8, 27, 64, ?
These are cubes of 1, 2, 3, and 4. The next is 5³ = 125.
36. Find the next number in the series:
8, 27, 64, 125, ?
These are 2³, 3³, 4³, and 5³. The next is 6³ = 216.
37. Find the next number in the series:
2, 6, 12, 20, ?
The pattern is n(n + 1): 1×2, 2×3, 3×4, 4×5. Next is 5×6 = 30.
38. Find the next number in the series:
6, 12, 20, 30, ?
The differences are 6, 8, 10; the next difference is 12. Thus 30 + 12 = 42.
39. Find the next number in the series:
2, 6, 12, 20, 30, ?
The differences are 4, 6, 8, and 10; the next difference is 12. Therefore, 30 + 12 = 42.
40. Find the next number in the series:
1, 4, 10, 19, ?
The differences are 3, 6, and 9; the next difference is 12. Thus, 19 + 12 = 31.
41. Find the next number in the series:
3, 8, 15, 24, ?
The differences are 5, 7, and 9; the next difference is 11. Therefore, 24 + 11 = 35.
42. Find the next number in the series:
2, 7, 14, 23, ?
The differences are 5, 7, and 9; the next difference is 11. So 23 + 11 = 34.
43. Find the next number in the series:
10, 13, 18, 25, ?
The differences are 3, 5, and 7; the next difference is 9. Hence, 25 + 9 = 34.
44. Find the next number in the series:
2, 3, 5, 8, 12, ?
The differences are 1, 2, 3, and 4; the next difference is 5. Thus, 12 + 5 = 17.
45. Find the next number in the series:
5, 7, 11, 17, 25, ?
The differences are 2, 4, 6, and 8; the next difference is 10. So the next term is 35.
46. Find the next number in the series:
100, 81, 64, 49, ?
These are descending squares: 10², 9², 8², 7². The next is 6² = 36.
47. Find the next number in the series:
121, 100, 81, 64, ?
These are descending squares: 11², 10², 9², 8². The next is 7² = 49.
48. Find the next number in the series:
2, 5, 10, 17, 26, ?
The differences are 3, 5, 7, and 9; the next difference is 11. Therefore, 26 + 11 = 37.
49. Find the next number in the series:
4, 7, 12, 19, 28, ?
The differences are 3, 5, 7, and 9; the next difference is 11. So the answer is 39.
50. Find the next number in the series:
1, 2, 6, 24, ?
Each term is multiplied by the next integer: 1×2, 2×3, 6×4, 24×5 = 120.
51. Find the next number in the series:
2, 6, 24, 120, ?
Each term is multiplied by 3, 4, 5; the next multiplication is by 6: 120 × 6 = 720.
52. Find the next number in the series:
3, 9, 27, 81, ?
Each term is multiplied by 3, so 81 × 3 = 243.
53. Find the next number in the series:
5, 15, 45, 135, ?
Each term is multiplied by 3; 135 × 3 = 405.
54. Find the next number in the series:
1, 5, 13, 29, ?
Each term follows ×2 + 3: 1×2+3=5, 5×2+3=13, 13×2+3=29; next is 29×2+3=61.
55. Find the next number in the series:
2, 7, 17, 37, ?
Each term follows ×2 + 3: 2×2+3=7, 7×2+3=17; next is 37×2+3 = 77.
56. Find the next number in the series:
4, 11, 25, 53, ?
Each term follows ×2 + 3: 4×2+3=11, 11×2+3=25, 25×2+3=53; next is 53×2+3 = 109.
57. Find the next number in the series:
6, 13, 27, 55, ?
Each term follows ×2 + 1: 6×2+1=13, 13×2+1=27, 27×2+1=55; next is 55×2+1 = 111.
58. Find the next number in the series:
20, 19, 17, 14, ?
The differences are −1, −2, and −3; the next difference is −4. Thus, 14 − 4 = 10.
59. Find the next number in the series:
50, 48, 44, 38, ?
The differences are −2, −4, and −6; the next difference is −8. Therefore, 38 − 8 = 30.
60. Find the next number in the series:
12, 24, 36, 48, ?
The common difference is 12; 48 + 12 = 60.
61. Find the next number in the series:
15, 30, 45, 60, ?
The common difference is 15; 60 + 15 = 75.
62. Find the next number in the series:
40, 35, 30, 25, ?
The common difference is −5; 25 − 5 = 20.
63. Find the next number in the series:
9, 12, 15, 18, ?
The common difference is 3; 18 + 3 = 21.
64. Find the next number in the series:
14, 28, 42, 56, ?
The common difference is 14; 56 + 14 = 70.
65. Find the next number in the series:
3, 9, 27, 81, ?
Each term is multiplied by 3; 81 × 3 = 243.
66. Find the next number in the series:
625, 125, 25, 5, ?
Each term is divided by 5; 5 ÷ 5 = 1.
67. Find the next number in the series:
729, 243, 81, 27, ?
Each term is divided by 3; 27 ÷ 3 = 9.
68. Find the next number in the series:
7, 10, 16, 25, ?
The differences are 3, 6, and 9; the next difference is 12. Thus, 25 + 12 = 37.
69. Find the next number in the series:
2, 9, 28, 65, ?
The pattern is n³ + 1: 1³+1=2, 2³+1=9, 3³+1=28, 4³+1=65; next is 5³+1=126.
70. Find the next number in the series:
3, 10, 29, 66, ?
The pattern is n³ + 2: 1³+2=3, 2³+2=10, 3³+2=29, 4³+2=66; next is 5³+2=127.
71. Find the next number in the series:
1, 6, 15, 28, ?
The differences are 5, 9, and 13; the next difference is 17. Therefore, 28 + 17 = 45.
72. Find the next number in the series:
13, 17, 21, 25, ?
The series increases by 4 each time, so the next term is 25 + 4 = 29.
73. Find the next number in the series:
14, 19, 24, 29, ?
The series increases by 5 each time, so the next term is 29 + 5 = 34.
74. Find the next number in the series:
15, 21, 27, 33, ?
The series increases by 6 each time, so the next term is 33 + 6 = 39.
75. Find the next number in the series:
16, 23, 30, 37, ?
The series increases by 7 each time, so the next term is 37 + 7 = 44.
76. Find the next number in the series:
17, 25, 33, 41, ?
The series increases by 8 each time, so the next term is 41 + 8 = 49.
77. Find the next number in the series:
18, 20, 22, 24, ?
The series increases by 2 each time, so the next term is 24 + 2 = 26.
78. Find the next number in the series:
19, 22, 25, 28, ?
The series increases by 3 each time, so the next term is 28 + 3 = 31.
79. Find the next number in the series:
20, 24, 28, 32, ?
The series increases by 4 each time, so the next term is 32 + 4 = 36.
80. Find the next number in the series:
1, 6, 11, 16, ?
The series increases by 5 each time, so the next term is 16 + 5 = 21.
81. Find the next number in the series:
2, 8, 14, 20, ?
The series increases by 6 each time, so the next term is 20 + 6 = 26.
82. Find the next number in the series:
3, 10, 17, 24, ?
The series increases by 7 each time, so the next term is 24 + 7 = 31.
83. Find the next number in the series:
4, 12, 20, 28, ?
The series increases by 8 each time, so the next term is 28 + 8 = 36.
84. Find the next number in the series:
5, 7, 9, 11, ?
The series increases by 2 each time, so the next term is 11 + 2 = 13.
85. Find the next number in the series:
6, 9, 12, 15, ?
The series increases by 3 each time, so the next term is 15 + 3 = 18.
86. Find the next number in the series:
7, 11, 15, 19, ?
The series increases by 4 each time, so the next term is 19 + 4 = 23.
87. Find the next number in the series:
8, 13, 18, 23, ?
The series increases by 5 each time, so the next term is 23 + 5 = 28.
88. Find the next number in the series:
9, 15, 21, 27, ?
The series increases by 6 each time, so the next term is 27 + 6 = 33.
89. Find the next number in the series:
10, 17, 24, 31, ?
The series increases by 7 each time, so the next term is 31 + 7 = 38.
90. Find the next number in the series:
11, 19, 27, 35, ?
The series increases by 8 each time, so the next term is 35 + 8 = 43.
91. Find the next number in the series:
12, 14, 16, 18, ?
The series increases by 2 each time, so the next term is 18 + 2 = 20.
92. Find the next number in the series:
13, 16, 19, 22, ?
The series increases by 3 each time, so the next term is 22 + 3 = 25.
93. Find the next number in the series:
14, 18, 22, 26, ?
The series increases by 4 each time, so the next term is 26 + 4 = 30.
94. Find the next number in the series:
15, 20, 25, 30, ?
The series increases by 5 each time, so the next term is 30 + 5 = 35.
95. Find the next number in the series:
16, 22, 28, 34, ?
The series increases by 6 each time, so the next term is 34 + 6 = 40.
96. Find the next number in the series:
17, 24, 31, 38, ?
The series increases by 7 each time, so the next term is 38 + 7 = 45.
97. Find the next number in the series:
18, 26, 34, 42, ?
The series increases by 8 each time, so the next term is 42 + 8 = 50.
98. Find the next number in the series:
19, 21, 23, 25, ?
The series increases by 2 each time, so the next term is 25 + 2 = 27.
99. Find the next number in the series:
20, 23, 26, 29, ?
The series increases by 3 each time, so the next term is 29 + 3 = 32.
100. Find the next number in the series:
1, 5, 9, 13, ?
The series increases by 4 each time, so the next term is 13 + 4 = 17.
Number series practice develops pattern recognition, calculation speed, and logical reasoning. Always check the differences, ratios, squares, cubes, and alternating operations before selecting an answer.
Reasoning MCQs
Practice important Topic wise Reasoning Questions with Answers for competitive exams.