This is another classic problem at Project Euler that can be solved with the old trick of top down programming, like so: PrimeFactors(number).DefaultIfEmpty(number).Max(); It's a nice solution, supposing PrimeFactors() actually returns all prime factors of any given number. But before getting there,...

Prime numbers have a good deal of practical applications (for example in cryptography) but let's face it, even if they would have none, they would still be the favorite toy of mathematicians . In Problem 7 of Project Euler , we are asked to find the 10001st element of the famous list, my approach was...