Odd Man Out And Series

Question:
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.

Question:
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.

Question:
3, 7, 6, 5, 9, 3, 12, 1, 15, (….)

[A].

18

[B].

13

[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.

Question:
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.

Question:
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.

Question:
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.

Question:
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.

Question:
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.

Question:
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.

Question:
125, 127, 130, 135, 142, 153, 165

[A].

130

[B].

142

[C].

153

[D].

165

Answer: Option D

Explanation:

Prime numbers 2, 3, 5, 7, 11, 13 are to be added successively.

So, 165 is wrong.