Question : Directions: Which number will replace the question mark (?) to complete the given series?
3, 7, 15, 31, 63, 127, ?

Option 1: 245

Option 2: 250

Option 3: 260

Option 4: 255


Team Careers360 12th Jan, 2024
Answer (1)
Team Careers360 15th Jan, 2024

Correct Answer: 255


Solution : Given:
3, 7, 15, 31, 63, 127, ?

Add 1 to twice the previous number to get the next number of the given series –
(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

So, the missing number is 255. Hence, the fourth option is correct.

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