Project Euler: Problems 3, 5, 8

Submission of Problems 3, 5, 8. For checking primes, I could have used the Prime class but I wanted to figure out how I would do it first. For production code I would likely go ahead and use the Prime class. 

Apparently there is also a regex to check for primes and I would research further into that also (http://www.noulakaz.net/weblog/2007/03/18/a-regular-expression-to-check-for-prime-numbers/).