Number Series Practicing Questions and Bit Banks for Bank Exams

Sakshi Education

Number series questions are based on arithmetic operations such as addition, subtraction, multiplication and division.
i. If the series increases gradually, it might be a case of addition.
ii. If the series decreases gradually, it might be a case of subtraction.
iii. If there is a sharp increase in the terms at one or two places in the series, it might be multiplication or combination (i.e. multiplicati-on along with addition or subtra-ction).
iv. If there is a sharp decrease in the terms at one or two places in the series, it might be division or combination (i.e. division along with addition or subtraction).
v. If the case is pure multiplication or division, there will be an exact ratio between the successive terms but it will not be same in case of combination.
In present exams, two models of number series are given.
I. Missing term: In this series one term will be missing. Based on the logic of the other terms we have to find out the missing term.
II. Wrong number: In this series, one term will be given wrong. We have to find out that wrong number.

PRACTICE QUESTIONS

Directions (1-15): What should come in place of the question mark (?) in the following number series?
1.   987 587 331 187 123 ?
   1) 104 2) 113 3) 107 4) 114
   5) None of these
A: 3
   -400 -256 -144 -64
   987 587 331 187 123 ?
   400 ® (20)2, 256 ® (16)2,
   144 ® (12)2, 64 ® (8)2
   The next value to be subtracted is 42.
   The next term in the series is
   123 - 42 = 123 - 16 = 107
   \ ? = 107
2.   365 728 2160 8532 42340 ?
   1) 253275   2)253280
   3) 253285     4) 253290
    5) 253295
A: 4
   - 1 - 8 - 27 - 64
   365 728 2160 8532 42340 ?
×2 ×3 ×4 ×5
   1 ® (1)3, 8 ® (2)3, 27 ® (3)3, 64 ® (4)3
   \The value to be subtracted from 42340 is (5)3 i.e.
   42340 - 125 = 42215
? = 42215 × 6 = 253290
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3.   62 177 512 1507 4482 ?
   1) 13396 2)13397 3) 13398 4) 13399 5) 13400
A:   2
   ×3 ×3 ×3 ×3
    62 177 512 1507 4482 ?
-9 - 19 - 29 - 39
   ? = 4482 × 3 - 49 =
   13446 - 49 = 13397
4.    21 12342 22543 30824 37385 ?
   1) 42422 2) 42424 3) 42426 4) 42428 5) 42430
A:   3
    21 12342 22543 30824 37385 ?
    +12321 +10201 +8281 + 6561
    = (111)2 = (101)2 = (91)2 = (81)2
   The perfect square to be added to the next term is (71)2 = 5041
   ? = 37385 + 5041 = 42426
5.   800 160 48 19.2 9.6 ?
   1) 6.48    2) 5.76    3) 5.12
   4) 4.84     5) 4.56
A:   2
   The sharp decrease from 800 to 160 indicates that, it might be division. But in series like this don't come to conclusion from the highest value. Take the lowest terms. They are decimal numbers. So it might be multipli-cation with decimal numbers.
   ×0.2 ×0.3 ×0.4 ×0.5
   800 160 48 19.2 9.6 ?
\? = 9.6 × 0.6 = 5.76
6.   63 95 119 135 143 ?
   1) 151   2) 157   3)162
   4) 168   5) None of these
A:   5
   The values are increasing gradually. It indicates addition.
   +32 +24 +16 +8
   63 95 119 135 143 ?
    The next value to be added is 0
   (8 - 8).
\? = 143 + 0 = 143
7.   4 20 101 357 982 ?
   1) 1632   2) 1848   3)2040
   4) 2278   5) 2412
A:   4
   4 20 101 357 982 ?
   +16 +81 +256 +625
   16 ® (2)4, 81 ® (3)4,
   256 ® (4)4, 625 ®(5)4
   \ ? = 982 + (6)4 = 982 + 1296 = 2278
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8.   14 50 166 522 1598 ?
   1) 4832   2) 4834   3)4836
   4) 4838   5) 4840
A:   2
    ×3 ×3 ×3 ×3
   14 50 166 522 1598 ?
   +8 +16 +24 +32
   \? = 1598 × 3 + 40 = 4794 + 40 = 4834
9.   4830 4556 4290 4032 3782 ?
   1) 3510   2) 3520   3)3530
   4) 3540   5) 3550
A:   4; The gradual decrease in the terms indicates subtraction.
   -274 -266 -258 -250
   4830 4556 4290 4032 3782 ?
\ ? = 3782 - 242 = 3540
10.   1320 1313 1288 1227 1106 ?
   1) 875   2) 880   3)885
   4) 890   5) 895
A:   5
-7 -25 -61 -121
   1320 1313 1288 1227 1106 ?
    7 = (2)3 - 1, 25 = (3)3 - 2,
   61 = (4)3 - 3, 121 = (5)3 - 4.
   \? = 1106 - (63 - 5)
   = 1106 - 211 = 895
11.   150 152 149 153 148 154 ?
   1) 155 2) 152     3) 147
   4) 149 5) None of these
A:   3
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   The series is increasing and decreasing alternately. So the operators used might be addition and subtraction.
   +2 -3 +4 - 5 +6
   150 152 149 153 148 154 ?
\ ? = 154-7= 147
12.   17 52 158 477 ? 4310
   1) 1433 2) 1432    3)1435
   4)1434 5) None of these
A:   3
    ×3 ×3 ×3
   17 52 158 477 ? 4310
   +1 +2 +3
    \?= 477×3+4=1431+4=1435
13.   3 22 ? 673 2696 8093
   1) 133 2) 155 3) 156 4) 134 5) None of these
A: 4
   ×7 ×4 ×3
   3 22 ? 673 2696 8093
+1 +4 +5
\? = 22 × 6 +2=132+2=134
   134×5+3=670+3=673
14.   6 13 38 ? 532 2675
   1) 129 2) 123 3)172
   4) 164 5) None of these
A:   1
    +7 +6 +5
   6 13 38 ? 532 2675
×1 ×2 ×5
    \? = (38 +5)×3= 43×3=129
   (129+4)×4+133×4=532
15. 286 142 ? 34 16 7
   1) 66 2) 72    3) 64
   4) 74 5) None of these
A:   5
   ÷2 ÷2 ÷2
   286 142 ? 34 16 7
-1 -1 -1
   \?=142÷2-1=71-1=70
   70÷2-1=35-1=34
Directions (16-30): In each question below, a number series is given in which one number is wrong. Find out the wrong number.
16. 3601 3602 1803 604
   154 36 12
   1) 3602   2)1803   3)604
   4) 154   5) 36
A:   4
÷1 ÷2 ÷3 ÷4 ÷6
   3601 3602 1803 604 154 36 12
+1 +2 +3 +3 +6
\? The wrong number is 154.
The actual series should be
   ÷1 ÷2 ÷3 ÷4 ÷5 ÷6
   3601 3602 1803 604 155 36 12
+1 +2 +3 +4 +5 +6
17.   4 12 42 196 1005 6066 42511
   1) 12       2) 42   3)1005
   4) 196   5) 6066
A:   2
    ×2 ×3 ×4 ×5 ×6 ×7
   4 12 42 196 1005 6066 42511
   +4 +6 +28 +25 +36 +49
   \? Wrong number is 42
   The actual series should be
   ×2 ×3 ×4 ×5 ×6 ×7
   4 12 45 196 1005 6066 42511
   +4 +9 +16 +25 +36 +49
18. 2 8 12 20 30 42 56
   1) 8       2) 42   3) 30
   4) 20       5) 12
A:   1
    +6 +4 +8 +10 +12 +14
   2 8 12 20 30 42 56
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   Wrong number is 8. It should be 6 in place of 8
19. 32 16 24 65 210 945 5197.5
   1) 946 2) 16 3) 24 4) 210 5) 65
A:   5
   ×0.5 ×1.5 ×2.7 ×3.2 ×4.5 ×5.5
   32 16 24 65 210 945 5197.5
The wrong number is 65.
The original series should be
    ×0.5 ×1.5 ×2.5 ×3.5 ×4.5 ×5.5
   32 16 24 60 210 945 5197.5
20.   7 13 25 49 97 194 385
   1) 13    2) 49   3) 97
   4) 194   5) 25
A: 4
    ×2 ×2 ×2 ×2 ×2 ×2
   7 13 25 49 97 194 385
-1 -1 -1 -1 -0 -3
   \? The wrong number is 194.
   The actual series should be
   ×2 ×2 ×2 ×2 ×2 ×2
   7 13 25 49 97 193 385
    -1 -1 -1 -1 -1 -1
21.   13 25 40 57 79 103 130
   1) 25 2) 40 3)57 4) 79 5) None
A:   3
    +12 +15 +17 +22 +24 +27
   13 25 40 57 79 103 130
   The values are Added should be 3 more than the value added previously.
   \ 57 is the wrong number
   The actual series should be
   +12 +15 +18 +21 + 24 +27
   13 25 40 58 79 103 130
22.   2 10 18 54 162 486 1458
   1) 18 2) 54 3) 162 4) 10 5) None
A:   4
   ×5 +8 ×3 ×3 ×3 ×3
   2 10 18 54 162 486 1458
   The wrong number is 10.
   The actual series should be
   ×3 ×3 ×3 ×3 ×3 ×3
   2 6 18 54 162 486 1458