Euler_10

/**
The sum of the primes below 10 is 2 + 3 + 5 + 7 = 17.

Find the sum of all the primes below two million.
1179908154
*/

public class EulerTen


{
  public static void main ( String[] args )
  {
    long sum = 17;
	  for(int i=10; i<=2000000; i++){
		  if(isPrime(i)) sum = sum + i;
	  }
	  System.out.println(sum);

  }


public static boolean isPrime ( int num )
  {
    boolean prime = true;
    int limit = (int) Math.sqrt ( num );
    //makes prime detection faster but not able to detect first 4 primes (2,3,5,7)
    if(num%2==0 || num%3==0  || num%5==0 || num%7==0) prime = false;

	if(prime == true){
    	for ( int i = 3; i <= limit; i+=2 )
    	{
      		if ( num % i == 0 )
      			{
        			prime = false;
					break;
     			 }
    	}
	}
    return prime;
  }

}