Question : Directions: Which of the following numbers will replace the question mark (?) in the given series?
3, 7, 15, 31, 63, 127, 255, ?
Option 1: 520
Option 2: 511
Option 3: 560
Option 4: 510
Correct Answer: 511
Solution :
Given:
3, 7, 15, 31, 63, 127, 255, ?
The pattern is as follows –
(3 × 2) + 1 = 6 + 1 = 7
(7 × 2) + 1 = 14 + 1 = 15
(15 × 2) + 1 = 30 + 1 = 31
(31 × 2) + 1 = 62 + 1 = 63
(63 × 2) + 1 = 126 + 1 = 127
(127 × 2) + 1 = 254 + 1 = 255
(255 × 2) + 1 = 510 + 1 = 511
So, 511 is the missing number of the series. Hence, the second option is correct.
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