Question

Which of the following numbers is a Mersenne prime? A: 90 B: 27 - 1 C: 211 - 1 D: 15

Answer 1

Answer:

  B:  2⁷-1 = 127

Step-by-step explanation:

A Mersenne prime is a prime of the form 2^n -1, where n is also a prime.

Among the answer choices, neither 90=2·3²·5 nor 15=3·5 is prime. Both 2⁷-1 = 127 and 2¹¹-1 = 2047 are of the right form, but 2047 = 23·89 is a composite number.

  2⁷-1 = 127 is a Mersenne prime