Q (1-5) - Find the missing number in the given series.
(1). 46080, 3840, 384, 48, 8, 2, ?
Ans: (A)
46080 /12 = 3840
3840 /10 = 384
384 /8 = 48
48 /6 = 8
8/4 = 2
2 /2 = 1
(2). 279936, 46656, 7776, 1296, 216, ?
Ans: (C)
Go on dividing by 6 to the next number
(3). 12, 38, 116, 350, 1052, ?
Ans: (D)
12
12 × 3 + 2 = 38
38 × 3 + 2 = 116
116 × 3 + 2 = 350
350 × 3 + 2 = 1052
1052 × 3 + 2 = 3158
(4). 2, 7, 10, 22, 18, 37, 26,?
Ans: (B)
There are two series here
2, 10, 18, 26, ... (Increase by 8)
7, 22, 37, ... (Increase by 15)
Hence, next term is 37+15 = 52
(5). 5,28,57,88,125
Ans: (C)
28=23+5
57=29+28
88=31+57
125=37+88
166=41+125
Q (6-10) - Find the wrong number in the following series.
6. 15, 16, 34, 105, 424, 2124, 12756
Ans: (E)
2nd term = (1st term) * 1 + 1 = 15 *1 + 1 = 16.
3rd term = (2nd term) * 2 + 2 = 16 * 2 + 2 = 34
4th term = (3th term) *3 + 3 = 34 * 3 + 3 = 105
5th term = (4th term) * 4 + 4 = 105 * 4 + 4 = 424
6th term = (5th term) * 5 + 5 = 424 * 5 + 5 = 2125
6th term should 2125 instead of 2124.
7. 15 46 63 71 75 77 78
Ans: (B)
In this question, if you start from the beginning, firstly the difference is 31, then the difference is 17, then the difference is 8. So there is no logic. If you start backwards,you can see that firstly, 1 is added, then 2 is added, then 4 is added, then 8,16 and 32 should have been added. So you have got the right clue. So 15 + 32 the first number should be 47 and afterwards, the series becomes + 16, + 8, + 4and so on.
8. 2,3,12,37,86,166,288
Ans: (C)
3-2=1
12-3=9
37-12=25
86-37=49
166-86=80(this must be 81=167-86=81)
so wrong number in the sequence is 166
difference between two sucessive numbers sequence would be
1,9,25,49,81,121(square of 1,3,5,7,9,11)
9. 13, 18, 25, 30, 37, 40
Ans: (D)
The differences between two successive terms from the beginning are 7, 5, 7, 5, 7, 5. So, 40 is wrong.
10. 3, 7, 15, 27, 63, 127, 255
Ans: (C)
Go on multiplying the number by 2 and adding 1 to it to get the next number.So, 27 is wrong.
(1). 46080, 3840, 384, 48, 8, 2, ?
- A. 1
- B. 1/64
- C. 1/8
- D. 2
- E. None of these
Ans: (A)
46080 /12 = 3840
3840 /10 = 384
384 /8 = 48
48 /6 = 8
8/4 = 2
2 /2 = 1
(2). 279936, 46656, 7776, 1296, 216, ?
- A. 60
- B. 46
- C. 36
- D. 66
- E. None of these
Ans: (C)
Go on dividing by 6 to the next number
- A. 1800
- B. 2200
- C. 2800
- D. 3158
- E. None of these
Ans: (D)
12
12 × 3 + 2 = 38
38 × 3 + 2 = 116
116 × 3 + 2 = 350
350 × 3 + 2 = 1052
1052 × 3 + 2 = 3158
- A. 42
- B. 52
- C. 46
- D. 62
- E.None of these
Ans: (B)
There are two series here
2, 10, 18, 26, ... (Increase by 8)
7, 22, 37, ... (Increase by 15)
Hence, next term is 37+15 = 52
(5). 5,28,57,88,125
- A.156
- B.147
- C.166
- D.186
- E. None of these
Ans: (C)
28=23+5
57=29+28
88=31+57
125=37+88
166=41+125
Q (6-10) - Find the wrong number in the following series.
6. 15, 16, 34, 105, 424, 2124, 12756
- A.16
- B.34
- C.105
- D.424
- E.2124
Ans: (E)
2nd term = (1st term) * 1 + 1 = 15 *1 + 1 = 16.
3rd term = (2nd term) * 2 + 2 = 16 * 2 + 2 = 34
4th term = (3th term) *3 + 3 = 34 * 3 + 3 = 105
5th term = (4th term) * 4 + 4 = 105 * 4 + 4 = 424
6th term = (5th term) * 5 + 5 = 424 * 5 + 5 = 2125
6th term should 2125 instead of 2124.
- A.15
- B.46
- C.63
- D.71
- E.75
Ans: (B)
In this question, if you start from the beginning, firstly the difference is 31, then the difference is 17, then the difference is 8. So there is no logic. If you start backwards,you can see that firstly, 1 is added, then 2 is added, then 4 is added, then 8,16 and 32 should have been added. So you have got the right clue. So 15 + 32 the first number should be 47 and afterwards, the series becomes + 16, + 8, + 4and so on.
- A.37
- B.86
- C.166
- D.288
- E.12
Ans: (C)
3-2=1
12-3=9
37-12=25
86-37=49
166-86=80(this must be 81=167-86=81)
so wrong number in the sequence is 166
difference between two sucessive numbers sequence would be
1,9,25,49,81,121(square of 1,3,5,7,9,11)
- A. 25
- B. 30
- C. 37
- D. 40
- E.None of these
Ans: (D)
The differences between two successive terms from the beginning are 7, 5, 7, 5, 7, 5. So, 40 is wrong.
- A.7
- B.15
- C.27
- D.63
- E.127
Ans: (C)
Go on multiplying the number by 2 and adding 1 to it to get the next number.So, 27 is wrong.