title: Find prime numbers in c#
body: <p>before I start asking, I will tell what I did.
  there was a problem, <a href="http://projecteuler.net/index.php?section=problems&amp;id=7" rel="nofollow">problem 3</a>, you can go to that link and see what it requires. 
  To solve it, i just wrote a function to find if that number is prime or not. Simple.</p>
  
  <p>But, problem 10 requires sum of all prime number under 2 million(2000000), I solve this by simply checking all numbers until 2m and see if its prime then add it to some variable.(if its prime)</p>
  
  <p>However, doing that takes so much time. and with so much time i mean hours. lots of hours. so I dont think my answer was right :)</p>
  
  <p>I googled the question before asking here, but I found no c#. closest one i can found was java and fortran, which i cant seem to realize the algorithm.</p>
  
  <p>Here I am, asking this. how you could do this ? checking every number till 2m and notice it if its prime is not fast way.(also this questions supposed to be calculated under 1 minute(by problem i mean, not by you lol) afaik)</p>
  
  <p>Thanks.</p>