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Odd Man Out and Series – Find Wrong No.

Insert the missing number.
1. 16, 33, 65, 131, 261, (….)
A. 523
B. 521
C. 613
D. 721

Answer: Option A

Explanation:

Each number is twice the preceding one with 1 added or subtracted alternatively.

So, the next number is (2 x 261 + 1) = 523.


2. 10, 5, 13, 10, 16, 20, 19, (….)
A. 22
B. 40
C. 38
D. 23

Answer: Option B

Explanation:

There are two series (10, 13, 16, 19) and (5, 10, 20, 40), one increasing by 3 and the other multiplied by 2.

3. 1, 4, 9, 16, 25, 36, 49, (….)
A. 54
B. 56
C. 64
D. 81

Answer: Option C

Explanation:

Numbers are 12, 22, 32, 42, 52, 62, 72.

So, the next number is 82 = 64.


4. 2, 4, 12, 48, 240, (….)
A. 960
B. 1440
C. 1080
D. 1920

Answer: Option B

Explanation:

Go on multiplying the given numbers by 2, 3, 4, 5, 6.

So, the correct next number is 1440.


5. 8, 7, 11, 12, 14, 17, 17, 22, (….)
A. 27
B. 20
C. 22
D. 24

Answer: Option B

Explanation:

There are two series (8, 11, 14, 17, 20) and (7, 12, 17, 22) increasing by 3 and 5 respectively.

6. 11, 13, 17, 19, 23, 29, 31, 37, 41, (….)
A. 43
B. 47
C. 53
D. 51

Answer: Option A

Explanation:

Numbers are all primes. The next prime is 43.
7. 8, 24, 12, 36, 18, 54, (….)
A. 27
B. 108
C. 68
D. 72

Answer: Option A

Explanation:

Numbers are alternatively multiplied by 3 and divided by 2.

So, the next number = 54 ÷ 2 = 27.

8. 2, 6, 12, 20, 30, 42, 56, (….)
A. 61
B. 64
C. 72
D. 70

Answer: Option C

Explanation:

The pattern is 1 x 2, 2 x 3, 3 x 4, 4 x 5, 5 x 6, 6 x 7, 7 x 8.

So, the next number is 8 x 9 = 72.

9. 4, -8, 16, -32, 64, (….)
A. 128
B. -128
C. 192
D. -192

Answer: Option B

Explanation:

Each number is the proceeding number multiplied by -2.

So, the required number is -128.

10. 7, 26, 63, 124, 215, 342, (….)
A. 481
B. 511
C. 391
D. 421

Answer: Option B

Explanation:

Numbers are (23 – 1), (33 – 1), (43 – 1), (53 – 1), (63 – 1), (73 – 1) etc.

So, the next number is (83 – 1) = (512 – 1) = 511.

11. 5, 10, 13, 26, 29, 58, 61, (….)
A. 122
B. 64
C. 125
D. 128

Answer: Option A

Explanation:

Numbers are alternatively multiplied by 2 and increased by 3.

So, the missing number = 61 x 2 = 122.

12. 15, 31, 63, 127, 255, (….)
A. 513
B. 511
C. 517
D. 523

Answer: Option B

Explanation:

Each number is double the preceding one plus 1.

So, the next number is (255 x 2) + 1 = 511.

13. 1, 8, 27, 64, 125, 216, (….)
A. 354
B. 343
C. 392
D. 245

Answer: Option B

Explanation:

Numbers are 13, 23, 33, 43, 53, 63.

So, the missing number is 73 = 343.

14. 3, 7, 6, 5, 9, 3, 12, 1, 15, (….)
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Find out the wrong number in the series.
A. 18
B. 13
1. 7, 8, 18, 57, 228, 1165, 6996
A. 8
B. 18
C. 57
D. 228
E. 1165

Answer: Option D

Explanation:

Let the given numbers be A, B, C, D, E, F, G.

Then, A, A x 1 + 1, B x 2 + 2, C x 3 + 3, D x 4 + 4, E x 5 + 5, F x 6 + 6 are the required numbers.

Clearly, 228 is wrong.

2. 1, 1, 2, 6, 24, 96, 720
A. 720
B. 96
C. 24
D. 6
E. 2

Answer: Option B

Explanation:

Go on multiplying with 1, 2, 3, 4, 5, 6 to get next number.

So, 96 is wrong.

3. 196, 169, 144, 121, 100, 80, 64
A. 169
B. 144
C. 121
D. 100
E. 80

Answer: Option E

Explanation:

Numbers must be (14)2, (13)2, (12)2, (11)2, (10)2, (9)2, (8)2.

So, 80 is wrong.

4. 445, 221, 109, 46, 25, 11, 4
A. 221
B. 109
C. 46
D. 25
E. 11

Answer: Option C

Explanation:

Go on subtracting 3 and dividing the result by 2 to obtain the next number.

Clearly, 46 is wrong.

5. 190, 166, 145, 128, 112, 100, 91
A. 100
B. 166
C. 145
D. 128
E. 112

Answer: Option D

Explanation:

Go on subtracting 24, 21, 18, 15, 12, 9 from the numbers to get the next number.

190 - 24 = 166
166 - 21 = 145
145 - 18 = 127 [Here, 128 is placed instead of 127]
127 - 15 = 112
112 - 12 = 100 ... and so on.

Therefore, 128 is wrong.

Find out the wrong number in the series.
6. 19, 26, 33, 46, 59, 74, 91
A. 26
B. 33
C. 46
D. 59
E. 74

Answer: Option B

Explanation:

Go on adding 7, 9, 11, 13, 15, 17 respectively to obtain the next number.

So, 33 is wrong. It must be 35

7. 1, 3, 10, 21, 64, 129, 356, 777
A. 10
B. 21
C. 64
D. 129
E. 356

Answer: Option E

Explanation:

A x 2 + 1, B x 3 + 1, C x 2 + 1, D x 3 + 1 and so on.

So, 356 is wrong.

8. 6, 12, 48, 100, 384, 768, 3072
A. 768
B. 384
C. 100
D. 48
E. 12

Answer: Option C

Explanation:

Each even term of the series is obtained by multiplying the previous term by 2.

2nd term = (1st term) x 2 = 6 x 2 = 12

4th term = (3rd term) x 2 = 48 x 2 = 96.

6th term = (5th term) x 2 = 384 x 2 =768.

4th term should be 96 instead of 100.

ix

9. 40960, 10240, 2560, 640, 200, 40, 10
A. 640
B. 40
C. 200
D. 2560
E. 10240

Answer: Option C

Explanation:

Go on dividing by 4 to get the next number.

So, 200 is wrong.

10. 3, 7, 15, 39, 63, 127, 255, 511
A. 7
B. 15
C. 39
D. 63
E. 127

Answer: Option C

Explanation:

Go on multiplying 2 and adding 1 to get the next number.

So, 39 is wrong.

Find out the wrong number in the series.
11. 64, 71, 80, 91, 104, 119, 135, 155
A. 71
B. 80
C. 104
D. 119
E. 135

Answer: Option E

Explanation:

Go on adding 7, 9, 11, 13, 15, 17, 19 respectively to obtain the next number.

So, 135 is wrong.

12. 15, 16, 34, 105, 424, 2124, 12756
A. 16
B. 34
C. 105
D. 424
E. 2124

Answer: Option E

Explanation:

2nd term = (1st term) x 1 + 1 = 15 x 1 + 1 = 16.

3rd term = (2nd term) x 2 + 2 = 16 x 2 + 2 = 34.

4th term = (3th term) x 3 + 3 = 34 x 3 + 3 = 105.

5th term = (4th term) x 4 + 4 = 105 x 4 + 4 = 424

6th term = (5th term) x 5 + 5 = 424 x 5 + 5 = 2125

6th term should 2125 instead of 2124.

13. 10, 26, 74, 218, 654, 1946, 5834
A. 26
B. 74
C. 218
D. 654
E. 1946

Answer: Option D

Explanation:

2nd term = (1st term) x 3 – 4 = 10 x 3 – 4 = 26.

3rd term = (2nd term) x 3 – 4 = 26 x 3 – 4 = 74.

4th term = (3th term) x 3 – 4 = 74 x 3 – 4 = 218.

5th term = (4th term) x 3 – 4 = 218 x 3 – 4 = 650.

5th term must be 650 instead of 654.

14. 2880, 480, 92, 24, 8, 4, 4
A. 480
B. 92
C. 24
D. 8
E. 4

Answer: Option B

Explanation:

Go on dividing by 6, 5, 4, 3, 2, 1 respectively to obtain the next number.

Clearly, 92 is wrong.

15. 3, 7, 15, 27, 63, 127, 255
A. 7
B. 15
C. 27
D. 63
E. 127

Answer: Option C

Explanation:

Go on multiplying the number by 2 and adding 1 to it to get the next number.

So, 27 is wrong.

C.-1

D.3

Answer: Option C

Explanation:

There are two series, beginning respectively with 3 and 7. In one 3 is added and in another 2 is subtracted.

The next number is 1 – 2 = -1.

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