Project Euler: Problem 1 (Possible refactorings and run time optimizations)

Question

I have been hearing a lot about Project Euler so I thought I solve one of the problems in C#. The problem as stated on the website is as follows:

If w

Answer 1

I like technielogys idea, here's my idea of a modification

static int Euler1 () 
{ 
  int sum = 0; 

  for (int i=3; i<1000; i+=3) 
  {
    if (i % 5 == 0) continue;
    sum+=i; 
  }
  for (int i=5; i<1000; i+=5) sum+=i; 

  return sum; 
} 

Though also comes to mind is maybe a minor heuristic, does this make any improvement?

static int Euler1 () 
{ 
  int sum = 0; 

  for (int i=3; i<1000; i+=3) 
  {
    if (i % 5 == 0) continue;
    sum+=i; 
  }
  for (int i=5; i<250; i+=5)
  {
    sum+=i;
  }
  for (int i=250; i<500; i+=5)
  {
    sum+=i;
    sum+=i*2;
    sum+=(i*2)+5;
  }

  return sum; 
}