Solution to problem 8.
Solution to problem 9.
Re-arranged everything. It's nice.
Made everything a bit faster by excluding factors already accounted for.
Added isPrime() function.
Optimized isPrime() and fixed a small error not checking for root as divisor.
Added solution to problem 7.
1 is not a prime.
Added solution to problem 10.
Added solution to problem 12.
Changed the main function to allow running a single problem.
Added solution to problem 11.