Module with functions to sum all prime numbers before a limit. Contains sequential and parallel versions. Functions:

• Hw.Primes.sum_primes/1: Returns the sum of all primes before the limit sequentially. Takes the limit as an argument.
• Hw.Primes.sum_primes_parallel/2: Takes 2 arguments, n and t. Sums all primes before n in t threads.

The algorithm used to sum prime numbers takes O(n^2) time, since it has to iterate through every number and for each one, to check if it's a prime number, it has to divide n by every number from 2 to √n.

Speed measurements (in seconds) for both versions of the algorithm with n = 5,000,000 and t = 20 (for the parallel version) are listed in the following table:

On average, the parallel version is 20.31 seconds faster than the sequential version, a 5.70 speed up.