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Aptitude - Odd Man Out and Series

Exercise : Odd Man Out and Series - Missing No.
Directions to Solve
Insert the missing number.
6.
11, 13, 17, 19, 23, 29, 31, 37, 41, (....)
43
47
53
51
Answer: Option
Explanation:
Numbers are all primes. The next prime is 43.
7.
8, 24, 12, 36, 18, 54, (....)
27
108
68
72
Answer: Option
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, (....)
61
64
72
70
Answer: Option
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, (....)
128
-128
192
-192
Answer: Option
Explanation:

Each number is the proceeding number multiplied by -2.

So, the required number is -128.

10.
7, 26, 63, 124, 215, 342, (....)
481
511
391
421
Answer: Option
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.

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