Number series is a form of series in which particular numbers are present in a particular order and missing numbers are to find out, nowadays number series is an important part of each and every government exams, especially in banks. It acquires a high alert.
Types
1. Addition series:
In this type of number series, specific numbers based on some pattern are added to get the next number.
Ex: 2, 6, 10, 14, 18, 22…..
2. Subtraction series:
In this type of number series, specific numbers based on some pattern are subtracted to get the next number.
Ex: 20, 17, 14, 11, 8…..
3. Multiplication series:
In this type of number series, specific numbers based on some pattern are multiplied to get the next number
Ex: 3, 9, 27…..
4. Division series: In this type of number series, specific numbers based on some pattern are divided to get the next number.
Ex: 216, 36, 6…..
5. Square series:
In this type of number series, each number is a perfect square of a particular number pattern.
Ex: 1, 4, 9, 16…..
6. Cube series:
In this type of number series, each number is a perfect cube of a particular number pattern.
Ex: 1, 8, 27, 64, 125…..
7. Fibonacci series:
In this type of number series, the next number is the addition of two previous numbers
Ex: 1, 2, 3, 5, 8, 13…..
8. Alternating series:
In this type of number series, successive terms increase and decrease alternatively, the possibilities of alternating series are it is the combination of two different series. Two different operations are performed on successive terms alternatively.
Ex: 15, 14, 19, 11, 23, 8, 27……
Model Questions
1. 117, 136, 154, 171, 187, ?
A) 202 B) 208 C) 210 D) 212 E) 214
Sol: 117 + 19 = 136
136 + 18 = 154
154 + 17 = 171
171 + 16 = 187
187 + 15 = 202
Ans: A
2. 5, 30, 150, ?, 1800, 3600
A) 520 B) 600 C) 560 D) 460 E) 420
Sol: 5 × 6 = 30
30 × 5 = 150
150 × 4 = 600
600 × 3 = 1800
1800 × 2 = 3600
Ans: B
3. 69120, ?, 864, 144, 36, 18
A) 5860 B) 5680 C) 4894 D) 5422 E) 6912
Sol: 69120 ÷ 10 = 6912
6912 ÷ 8 = 864
864 ÷ 6 = 144
144 ÷ 4 = 36
36 ÷ 2 = 18
Ans: E
4. 12, 18, 36, 90, 270, ?
A) 945 B) 245 C) 215 D) 285 E) 305
Sol: 12 × 1.5 = 18
18 × 2 = 36
36 × 2.5 = 90
90 × 3 = 270
270 × 3.5 = 945
Ans: A
5. 31, 43, 57, ?, 91, 111
A) 48 B) 1 C) 56 D) 73 E) 45
Sol: 31 + 12 = 43
43 + 14 = 57
57 + 16 = 73
73 + 18 = 91
91 + 20 = 111
Ans: D
6. ?, 39, 117, 351, 1053, 3159
A) 26 B) 11 C) 13 D) 14 E) 33
Sol: 13 + (13 × 2) = 39
39 + (39 × 2) = 117
117 + (117 × 2) = 351
351 + (351 × 2) = 1053
1053 + (1053 × 2) = 3159
Ans: C
7. 121, 134, 151, 170, 193, ?
A) 212 B) 216 C) 222 D) 227 E) 230
Sol: 121 + 13 = 134
134 + 17 = 151
151 + 19 = 170
170 + 23 = 193
193 + 29 = 222
Ans: C
8. 32, 80, ?, 840, 3360, 15120
A) 320 B) 360 C) 240 D) 420 E) 480
Sol: 32 × 2.5 = 80
80 × 3 = 240
240 × 3.5 = 840
840 × 4 = 3360
3360 × 4.5 = 15120
Ans: C
9. 13, ?, 326, 522, 747,1003
A) 157 B) 997 C) 119 D) 127 E) 126
Sol: 13 + 144 (122) = 157
157 + 169 (132) = 326
326 + 196 (142) = 522
522 + 225 (152) = 747
747 + 256 (162) = 1003
Ans: A
10. 99, 96, 80, ?, −1341
A) −41 B) −48 C) −45 D) −63 E) −69
Sol: 99 − 31 = 96
96 − 42 = 80
80 − 53 = −45
− 45 − 64 = −1341
Ans: C
11. ?, 289, 169, 121, 49, 25
A) 324 B) 361 C) 256 D) 225 E) 144
Sol: 192 = 361
172 = 289
132 = 169
112 = 121
72 = 49
52 = 25
Ans: B
12. 15, 82, 151, ?, 295, 370
A) 222 B) 256 C) 268 D) 231 E) 280
Sol: 15 + 67 = 82
82 + 69 = 151
151 + 71 = 222
222 + 73 = 295
295 + 75 = 370
Ans: A
13. 21, 42, ?, 504, 2520, 15120
A) 111 B) 126 C) 117 D) 120 E) 109
Sol: 21 × 2 = 42
42 × 3 = 126
126 × 4 = 504
504 × 5 = 2520
2520 × 6 = 15120
Ans: B
14. 4826809, 371293, 28561, 2197, 169, ?
A) 13 B) 31 C) 22 D) 40 E) 19
Sol:
Ans: A
15. 29, 42, 57, 74, 93, ?
A) 120 B) 114 C) 131 D) 135 E) 130
Sol: 9 × 3 + 2 = 29
10 × 4 + 2 = 42
11 × 5 + 2 = 57
12 × 6 + 2 = 74
13 × 7 + 2 = 93
14 × 8 + 2 = 114
Ans: B
► 242, 252, 260, 266, 270, ?
A) 343 B) 342 C) 272 D) 340 E) 344
Sol: 22 × 11 = 242
21 × 12 = 252
20 × 13 = 260
19 × 14 = 266
18 × 15 = 270
17 × 16 = 272
Ans: C
►10, 25, ?, 393.75, 2165.625, 14076.5625
A) 25.25 B) 45.5 C) 65 D) 87.5 E) 85.5
Sol: 10 × 2.5 = 25
25 × 3.5 = 87.5
87.5 × 4.5 = 393.75
393.75 × 5.5 = 2165.625
2165.625 × 6.5 = 14076.5625
Ans: D
► 16, ?, 140, 630, 3465, 22522.5
A) 40 B) 22 C) 52 D) 80 E) 83.5
Sol: 16 × 2.5 = 40
40 × 3.5 = 140.0
140 × 4.5 = 630.0
630 × 5.5 = 3465.0
3465 × 6.5 = 22522.5
Ans: A
► 50, 60, 75, 97.5, ?, 184.275
A) 125.25 B) 131.625 C) 130 D) 141.625 E) 156
Sol: 50 × 1.2 = 60
60 × 1.25 = 75
75 × 1.3 = 97.5
97.5 × 1.35 = 131.625
131.625 × 1.4 = 184.275
Ans: B
► 1330, 1726, 2194, 2740, 3370, ?
A) 3110 B) 4090 C) 4160 D) 4240 E) 3200
Sol: 113 − 11 = 1330
123 − 21 = 1726
133 − 31 = 2194
143 − 41 = 2740
153 − 51 = 3370
163 − 61 = 4090
Ans: B
