What should come in place of the question mark 39 39 in the following number series 15 31 63 127 511...........

Quantitative Aptitude (SBI-CL) Number series

What should come in place of the question mark '?' in the following number series?

15, 31, 63, 127, ?, 511

This questions was previously asked in

SBI Clerk Prelims (11 Jul, 2021 Shift 1)

254

258

245

255

None of these

- The given series is: 15, 31, 63, 127, ?, 511.

- Observing the pattern:

- 15 is 2^4 - 1.

- 31 is 2^5 - 1.

- 63 is 2^6 - 1.

- 127 is 2^7 - 1.

- Continuing this pattern:

- The next term should be 2^8 - 1.

- Calculating that gives 255.

- Next term after the missing one:

- 511 is 2^9 - 1 which fits the pattern.

- Option 4: 255 matches this sequence and is indeed the correct answer.

Therefore, the correct answer is:

- Option: 4 - 255

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