The sum of the primes below 10 is 2 + 3 + 5 + 7 = 17. Find the sum of all the primes below two million.

SumOfPrimes.java

public class SumOfPrimes {
	public static long calculate(int n){
		long sum=2;
		for(int i=3;i<n;i++)
			if(isPrime(i))
				sum+=i;
		return sum;
	}
	private static boolean isPrime(int p){
		for(int i=2;i<=Math.sqrt(p);i++)
			if(p%i==0) return false;
		return true;
	}
}

SumOfPrimesTest.java

public class SumOfPrimesTest {
	@Test
	public void testCalculate() {
		assertEquals(17, SumOfPrimes.calculate(10));
		assertEquals(142913828922L, SumOfPrimes.calculate(2000000));
	}
}