Thread: why do i get 5050?

Code:

#include <iostream>
#include <stdlib.h>
#include <string>
using namespace std;

int main(int argc, char *argv[])
{
int x = 0;
int i;
for (i = 1; i <= 100; i++){
    x += i;
}
cout << x << endl;    

  system("PAUSE");	
  return 0;
}

how i get 5050 out of this? the tutorial i got i from doesn't tell me anything about it and im very confused.