1. NUMBER SERIES
1.1 Introduction
1.2 Number Series
1.1 INTRODUCTION
Under this head following types of questions are asked-
1. Number Series
2. Alphabet Series
3. Letter Series
1.2 Nubmer Series
In this type a number series is given in which either next term is asked or some wrong term which does not follown the series is to find out.
Under this head following types of series are given-
1.2.1 Arithmetic progression
In this type of series the difference of two consecutive terms in same. Sometimes series are so given that the difference of two terms is same.
Example 1.
In the following series find the number in place of question mark.
15, 22, 29, 36, ?, 50, 57
(A) 43 (B) 42 (C) 40 (D) 44
Answer with Explanation (A) :
Example 2.
In the following series find the term in place of question mark ?
15, 30, 60, 105, 165, ?
(A) 210 (B) 220 (C) 230 (D) 240
Answer with explanation (D) :
1.2.2 Geometric Progression
In this type of series the ratio of consecutive terms is same.
Example 1.
In the following series which number will replace the question mark ?
4, 32, 16, 128, 64, ?
(A) 612 (B) 512 (C) 362 (D) 412
Answer with explanation (B) :
1.2.3 Mixed Series
In this type of series, both types of series A.P. and G.P. are together.
Example
In the following series, which number will replace the questions mark ?
2, 5, 12, 39, 160, 805, ?
(A) 4936 (B) 4930 (C) 4830 (D) 4836
Answer with explanation (D) :
1.2.4 Compound Series
In this type of series, it is a mixture of two or more than two series.
Example : In following series, which number will replace the question mark ?
4, 2, 5, 4, 7, 6, 10, 8, 14, ?
(A) 10 (B) 12 (C) 18 (D) 19
Answer with explanation (A) :
1.2.5 Series of Prime Numbers
In this typeof series, the difference of two consecutive numbers is a prime number, or each term contains a prime number.
Example:
In the following series, which number will replace the question mark ?
23, 29, 31, 37, 41, 43, ?
(A) 45 (B) 53 (C) 47 (D) 49
Answer with explanation (C) : On looking the series we see that each number of the series is a prime number and each subsequent
term is the next prime number. Hence, in place of question mark the next prine number to 43 will come. But the next prime number
after 43 is 47. Hence, 47 will replace the question mark.
1.2.6 Series based on squares and cube
In this type of series the difference between two consecutive numbers will always be in the form of a square or a cube or the terms
will be in the form of square or cube.
Example 1.
Which number will replace the question mark in the following series ?
1, 4, 9, 16, 25, 36, ?
(A) 40 (B) 45 (C) 49 (D) 47
Answer with explanation (C) :
Example 2.
In the following series which number will replace the question mark ?
0, 6, 24, 60, 120, 210, ?
(A) 336 (B) 343 (C) 300 (D) 332
Answer with explanation (A) :
EXERCISE-I
Directions - (Q 1- 45) In the following series find the number in place of question mark?
1. 23, 19, ?, 12, 9.
(A) 14 (B) 15 (C) 16 (D) 17
3. 25, 22, 30, ?, 35.
(A) 27 (B) 26 (C) 28 (D) 29
4. 1, 2, 6, 24, __
(A) 60 (B) 95 (C) 120 (D) 150
5. 29, 24, 26, 21, 23, ?
(A) 20 (B) 19 (C) 17 (D) 18
6. 3, 5, 6, 8, 11, 13, ?
(A) 17 (B) 18 (C) 15 (D) 20
7. 2, 8, 14, 26, 38, 56, ?
(A) 78 (B) 80 (C) 74 (D) 75
8. 2, 6, 8, 10, 10, 16, 20, 22, 24, 24, 30, ?
(A) 34 (B) 36 (C) 32 (D) 30
9. 2, 4, 12, 6, 12, 36, 18, 36, 108, ?
(A) 72 (B) 54 (C) 90 (D) 108
10. 2, 7, 15, 26, 40, 57, ?
(A) 80 (B) 81 (C) 75 (D) 77
11. 2, 5, 11, ?, 47.
(A) 17 (B) 18 (C) 21 (D) 23
12. 11, 5, 20, 12, ?, 26, 74, 54.
(A) 30 (B) 38 (C) 48 (D) 28
13. 324, 289, 256, 225, 196, ?
(A) 196 (B) 121 (C) 144 (D) 169
14. 1, 4, 7, 10, ?, 16, 19, ?.
(A) 13, 22 (B) 11, 22 (C) 13, 21 (D) 13, 23
15. 5, 13, ?, 109, 325, 973.
(A) 39 (B) 36 (C) 37 (D) 35
16. 1, 4, 10, ?, 46.
(A) 20 (B) 22 (C) 24 (D) 19
17. 2, 5, 4, 8, 11, 10, ?
(A) 15 (B) 13 (C) 12 (D) 14
18. 17, 39, 69, 107, 153, ?.
(A) 180 (B) 182 (C) 170 (D) 207
19. ?, 16, 36, 76, 156.
(A) 6 (B) 4 (C) 3 (D) 5
20. ?, 5, 13, 29, 61.
(A) 2 (B) 1 (C) 3 (D) 0
21. 2, ?, 6, 15, 45, .
(A) 4 (B) 5 (C) 7 (D) 3
22. 4, 7, 13, ?, 34, 49.
(A) 20 (B) 22 (C) 24 (D) 21
23. 3, 7, 11, 19, 27, 39, ?.
(A) 53 (B) 55 (C) 52 (D) 51
24. ?, 3, 3, 9, 27, 243.
(A) 0 (B) 2 (C) 1 (D)
25. 9, 22, 48, 87, ?.
(A) 139 (B) 152 (C) 126 (D) 132
26. 2, 7, 24, 99, 498, ?.
(A) 2994 (B) 2985 (C) 2988 (D) 2991
27. 12, 32, 72, 152, __
(A) 312 (B) 325 (C) 515 (D) 613
28. 5, 15, 28, 44, 63, 85, ?.
(A) 125 (B) 105 (C) 110 (D) 120
29. 0, 4, 5, 9, 12, 16, 21, 25, 32, 36, ?.
(A) 42 (B) 45 (C) 40 (D) 43
30. 1, 8, 15, 29, 43, 64, ?.
(A) 75 (B) 84 (C) 92 (D) 85
31. 840, 168, 42, 14, 7, __
(A) 1 (B) 7 (C) 9 (D) 1/7
32. 2, 8, 24, 12, 48, 144, 72, 288, 864, ?.
(A) 432 (B) 1728 (C) 428 (D) 1724
33. 5, 11, 24, ?, 106, 217.
(A) 52 (B) 50 (C) 49 (D) 51
34. 48, 32, 24, 20, 18, ?.
(A) 14 (B) 17 (C) 18 (D) 16
35. 4, 31, 62, 99, 144, 199, ?.
(A) 266 (B) 259 (C) 267 (D) 269
36. 10, 13, 19, 30, 48, 75, 113, ?.
(A) 167 (B) 166 (C) 164 (D) 162
37. 3, 1, 6, 3, 24, 18, 144, ?.
(A) 144 (B) 162 (C) 180 (D) 126
38. 0, 1, 1, 2, 3, 5, 8, 13, ?.
(A) 19 (B) 17 (C) 20 (D) 21
39. 54, 53, 49, 40, 24, ?.
(A) 0 (B) -1 (C) 3 (D) 2
40. 35, 36, 40, 49, 65, 90, ?.
(A) 116 (B) 120 (C) 132 (D) 126
41. 3, 5, 4, 7, 5, 9, 6, 11, ?.
(A) 7 (B) 9 (C) 8 (D) 10
42. 99, 51, 27, 15, 9, ?.
(A) 4 (B) 5 (C) 6 (D) 3
43. 3, 3, 6, 18, 72, ?.
(A) 288 (B) 360 (C) 144 (D) 216
45. 1, 4, 2, 8, 6, 24, 22, 88, __
(A) 86 (B) 90 (C) 154 (D) 352
Directions - (Q. 46-50) In each of the questions, find the wrong number in the series.
46. 2, 9, 28, 65, 125, 217,
(A) 2 (B 28 (C) 125 (D) 217
47. 0, 8, 7, 16, 14, 24, 22, 32.
(A) 22 (B) 14 (C) 24 (D) 32
48. 2, 5, 10, 50, 500, 5000,
(A) 5 (B) 10 (C) 50 (D) 5000
49. 1, 11, 22, 34, 47, 61, 76, 93.
(A) 93 (B) 1 (C) 34 (D) 76
50. 297, 272, 245, 216, 185, 153, 117.
(A) 117 (B) 153 (C) 185 (D) 216
ANSWER KEY
1. (B) 2. (D) 3. (A) 4. (C) 5. (D) 6. (B)
7. (C) 8. (A) 9. (B) 10. (D) 11. (D) 12. (B)
13. (D) 14. (A) 15. (C) 16. (B) 17. (D) 18. (D)
19. (A) 20. (B) 21. (D) 22. (B) 23. (D) 24. (C)
25. (A) 26. (D) 27. (A) 28. (C) 29. (B) 30. (D)
31. (B) 32. (A) 33. (D) 34. (B) 35. (A) 36. (C)
37. (B) 38. (D) 39. (B) 40. (D) 41. (A) 42. (C)
43. (B) 44. (D) 45. (A) 46. (C) 47. (A) 48. (D)
49. (A) 50. (B)