Program to find time difference in calculating 100,000 prime numbers single and multithreaded

ThreadTest.java

class ThreadTest
{
	public static void main(String [] args)
	{
		MyThread t1 = new MyThread(0);
		MyThread t2 = new MyThread(0);
		
		System.out.println("Time difference calculating 100000 prime numbers, single/multithreaded:");
		
		long start_time = System.nanoTime();
		t1.run();
		t2.run();
		long end_time = System.nanoTime();
		double difference = (end_time - start_time)/1e9;
		double roundOff = Math.round(difference * 100.00) / 100.00;
		System.out.println("Simultaneous duration: "+roundOff+" seconds");
		
		start_time = System.nanoTime();
		t1.run();
		t1.interrupt();
		t2.run();
		t2.interrupt();
		end_time = System.nanoTime();
		difference = (end_time - start_time)/1e9;
		roundOff = Math.round(difference * 100.00) / 100.00;
		System.out.println("Series duration: "+roundOff+" seconds");

	}
}

class MyThread extends Thread
{
	private int startpoint, status = 1, num = 3;

	public MyThread(int s)
	{
		this.startpoint = s;
	}

	@Override
	public void run()
	{
		{
			
			for ( int count = startpoint; count <= 100000; )
			{
				for ( int j = 2 ; j <= Math.sqrt(num) ; j++ )
				{
					if ( num%j == 0 )
					{
						status = 0;
						break;
					}
				}
				if ( status != 0 )
				{
					// System.out.println(num);
					count++;
				}
				status = 1;
				num++;
			}   
		}
	}
}