Which number will replace the question mark mark (?) to complete the given series?
3, 7, 15, 31, 63, 127, ?
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 i.e. 255.
Given series: 3, 7, 15, 31, 63, 127, ?
3 × 2 + 1 = 7; 7 × 2 + 1 = 15; 15 × 2 + 1 = 31; 31 × 2 + 1 = 63; 63 × 2 + 1 = 127; 127 × 2 + 1 = 255