Project Euler: Problem 7

By listing the first six prime numbers: 2, 3, 5, 7, 11, and 13, we can see that the 6th prime is 13.

What is the 10001st prime number?

– Project Euler Problem 7

Solution

This will be a very quick one, thanks to the prime number generator created earlier for problem 3. All we need is actually this one line of code:

var answer = new Eratosthenes().Take(10001).Last();

And that's it. It takes around 50 milliseconds, which is totally acceptable I would say. It can be sped up quite a bit though if we find a more efficient prime number generator. This, however, I will try to do in a later problem.