+592 a Mersenne prime is a prime number one less than a power of two
27 = 128 which means there are 6 number that can be a Mersenne prime less than 100:
21 - 1 = 1, which isn't prime
22 - 1 = 3, which is prime
23 - 1 = 7, which is prime
24 - 1 = 15, which isnt prime
25 - 1 = 31, which is prime
26 - 1 = 63, which isnt prime
this means there are 3 Mersenne primes that are less than 100
