Reasoning 4 Bank Exams

Number Series

Series is divided into two types. One is Number series and another one is Letter series. In Bank clerk exams 5 questions are covering from number series.
Number series tests present nume rical sequences that follow a logical rule which is based on elementary ar-ithmetic. An initial sequence is given from which the rule is to be deduced. You are then asked to predict the next number that obeys the rule.

Some practice questions
Directions(1–5): What should come in place of question mark (?) in the following number series.
(SBI clerk 6-1-2008)
1. 12, 6.5, 7.5, 12.75, 27.5, 71.25, ?
1) 225.75 2) 216.75
3) 209.75 4) 236.75
5) 249.75

2. 16, 24, 36, 54, 81, 121.5, ?
1) 182.25 2) 174.85
3) 190.65 4) 166.55
5) 158.95

3. 12, 12, 18, 45, 180, 1170,?
1) 13485 2) 14675
3) 15890 4) 16756
5) 12285

4. 22, 23, 27, 36, 52, 77, ?
1) 111 2) 109 3) 113 4) 117 5)115

5. 16, 14, 24, 66, 256, 1270, ?
1) 8564 2) 5672 3) 4561 4) 7608 5) 6340
Key (1–5)

1. 2 The given number series is based on the following pattern
12×0.5+0.5 = 6.5
6.5×1+1 = 7.5
7.5×1.5 +1.5 = 12.75
12.75 ×2 +2 = 27.5
27.5×2.5+2.5 = 71.25 and
71.25×3+ 3 = 216.75
So the ans is 216.75

2. 1 The given number series is based on the following pattern

16 ×= 8 × 3=24

24 ×=12×3= 36

36 ×= 18×3 =54

54 ×=27×3 =81

81×= 121.5 then

121.6×= 182.25
So the ans is 182.25

3. 5. The given number series is based on the following pattern.
12×1=12
12 ×1.5 =18
18 × 2.5= 45
45×4= 180
180×6.5 = 1170
Here each no multiply with 1, 1.5, 2.5, 4, 6.5, __ In this series the sum any two no's is third no. So last no is 4+ 6.5 = 10.5, now last no multiply with 10.5
1170 ×10.5 = 12285
So the ans is 12285

4. 3 Here given number series is based on the following pattern
22+12=22+1=23
23+22=23+4=27
27+32=27+9=36
36+42=36+16=52
52+52=52+25=77 and
77+62=77+36=113
So the answer is 113

5. 4 The given number series is based on the following pattern
16×1–2=14
14×2–4=24
24×3–6=66
66×4–8=256
256×5–10=1270 and
1270×6–12=7608
So the ans is 7608
Directions(6–10): In the followi-ng number series, a wrong number is given. Find out that wrong number. (SBI Clerk 10-2-2008)

6. 2, 11, 38, 197, 1172, 8227, 65806
1) 11 2) 38
3) 197 4) 1172
5) 8227

7. 16, 19, 21, 30, 46, 71, 107
1) 19 2) 21
3) 30 4) 46 5) 71

8. 7, 9, 16, 25, 41, 68, 107, 173
1) 107 2) 16
3) 41 4) 68 5) 25

9. 4, 2, 3.5, 7.5, 26.25, 118.125
1) 118.125 2) 26.25
3) 3.5 4) 2 5) 7.5

10. 16, 4, 2, 1.5, 1.75, 1.875
1) 1.875 2) 1.75
3) 1.5 4) 2 5) 4
Key (6–10)

6. 4 The series is based on the following pattern
2 ×3 + 5 =11
11× 4–6 = 38
38×5 + 7 =197
197×6 –8 =1174: it is not 1172
1174× 7 + 9 =8227
8227× 8–10 =65806
Clearly 1172 is the wrong number and it should be replaced by 1174

7. 1 The series is based on the following pattern
16 + 12 = 17 but not 19
17 + 22 = 21
21 + 32 = 30
30 + 42 = 46
46 + 52 = 71
71 + 62 = 107
Clearly 19 should be replaced by 17

8. 4 The series is based on the following pattern.
7+9=16
9+16=25
25+41=66 but not 68
41+66=107
66+107=173
So 68 should be replaced by 66

9. 3 The series is based on the following pattern
4×0.5 = 2
2×1.5 = 3 but not 3.5
3×2.5 = 7.5
7.5 ×3.5 = 26.25
26.25×4.5 = 118.25
So 3.5 should be replaced with 3

10. 2 The series is based on the following pattern.
16 × 0.25 =4
4× 0.5 =2
2 × 0.75 =1.5
1.5× 1.00 =1.5 but not 1.75
1.5×1.25= 1.875
So 1.75 should be replaced by 1.5

Directions (11–13): What will come in place of the question mark (?) in the following number series?
(Union Bank of India 6-2-2011)
11. 17, 98, 147, 172, 181, ?
1) 180 2) 192 3) 184 4) 182 5) None of these

12. 11, 19, 31, 47, 67, ?
1) 80 2) 81 3) 86 4) 96 5)None of these
13. 748, 460, 316, 244, 208, ?
1) 180 2) 190 3) 172 4) 182 5) None of these
Key (11–13)

11. 4 The series is based on the following pattern.
17+92 = 98
98+72 =147
147+52 =172
172+32 =181
181+12 =182
So the ans is 182

12. 5 The series is based on the following pattern.
11 + 8 = 19
19 + 12 = 31
31 + 16 = 47
47 + 20 = 67
67 + 24 =91
So the ans is 91

13. 2 The series is based on the following pattern.
748 – 288 = 460
460 – 144= 316
316 –72 = 244
244 –36 = 208
208 –18 = 190

Directions (14–16): What will come in place of the question mark (?) in the following number series. (Corporation Bank Clerk 12-9-2010)
14. 12, 16, 24, 36, 52, ?
1) 80 2) 76
3) 72 4) 82 5) None of these

15. 17, 21, 37, 73, 137, ?
1) 246 2) 236 3) 217 4) 237
5) None of these

16. 620, 412, 308, 256, 230, ?
1) 217 2) 227
3) 207 4) 234
5) None of these

Key (14–16)
14. 3 The series in the following pattern.
12 + 4 = 16
16 + 8 = 24
24 + 12 = 36
36 + 16 = 52 and
52 + 20 = 72

15. 4 The series in the following pattern.
17 + 22 =21
21 + 42 = 37
37 + 62 = 73
73 + 82 = 137
137 +102 = 237

16. 1 The series in the following pattern.
620 – 208 = 412
412 –104 = 308
308 –52 = 256
256–26 =230 and
230–13 = 217

Directions (17 and 18): What will come in place of the question mark (?) in the following number series. (Bank of Baroda 6-6-2010)

17. 153, 150, 144, 132, 108, ?
1) 60 2) 84
3) 54 4) 72

5) None of these
18. 31, 40, 58, 85, 121, ?
1) 166 2) 175
3) 157 4) 184
5) None of these

Key (17–18)
17. 1 The series in the following pattern.
153–3 = 150
150–6 = 144
144–12 = 132
132–24 =108
108 – 48 =60
So the ans is 60

18. 1 The series in the following pattern.
31 + 9 =40
40 +18 = 58
58 +27 =85
85 + 36 =121
121 + 45 =166

Directions (19–23):What should come in place of the question mark (?) in the following number series?
19. 36, 37, 46, 71, ?, 201, 322
1) 120 2) 107
3) 135 4) 96
5) None of these

20. 12, 20, 100, ?, 8900, 88900, 888900
1) 1000 2) 900
3) 800 4) 500
5) None of these

21. 7, 7, 14, 42, 168, ?, 5040
1) 672 2) 850
3) 740 4) 800
5) None of these

22. 21, 30, 12, 39, 3, ?, -6
1) 66 2) 12
3) 48 4) 75
5) None of these

23. 10, 24, 52, ?, 220, 444, 892
1) 104 2) 98
3) 112 4) 108
5) None of these

Key (19–23)
19. 1 The series in the following pattern.
36 + 11 = 37
37 + 32 = 46
46 + 52 =71
71 + 72 = 120
120 + 92 = 201
201 +112 = 322
So the ans is 120

20. 2 The series in the following pattern.
12 + 8 = 20
20 +80 = 100
100+800 = 900
900 + 8000 = 8900
8900 + 80000 = 88900
88900 + 800000 = 888900

21. 5 The series in the following pattern.
7×1 = 7
7×2 = 14
14×3 = 42
42× 4 = 168
168× 5 = 840
840×6 =5040

22. 3 The series in the following pattern.
21 + 9 = 30
30 – 18 = 12
12 + 27 = 39
39 – 36 = 3
3 + 45 = 48
48 – 54 = –6

23. 4 The series in the following pattern.
10×2 + 4 = 24
24×2 + 4 = 52
52×2 + 4 = 108
108×2 + 4 = 220
220×2 + 4 = 444
444×2 + 4 = 892