Question

Replace the ? with appropriate number in the given series.

7, 13, 27, 53, ?, 213

• A. 106
• B. 107
• C. 105
• D. 108

Answer 1

Answer: (B)

107

Looking at the terms of the series, we can conclude that:

13 = 2 $\times$ 7 - 1

27 = 2 $\times$ 13 + 1

53 = 2 $\times$ 27 - 1

So next term should be :

2 $\times$ 53 + 1 = 107

And next to it:

2 $\times$ 107 - 1 = 213 (which is given in the series)

So, correct answer in the option B.