Algorithm to find all primes from 2 to 1000 not working

Question

Here\'s a piece of code to compute all primes from 2 to 1000 using the statement, that a number n is a prime number iff:

In the first version I think that I

Answer 1

Java doubles (i.e., the outputs of pow) do not represent large numbers precisely enough to yield a correct remainder. You should switch to modular exponentiation.