Java Program to convert this duration to the total length in milliseconds

import java.time.Duration;
public class Demo {
	public static void main(String[] args) {
		Duration d1 =  Duration.ofDays(20);
		Duration d2 =  Duration.ofHours(100);
		Duration d3 =  Duration.ofMinutes(150);
		System.out.println("Milliseconds in 20 days = "+d1.toMillis());
		System.out.println("Milliseconds in 100 hours = "+d2.toMillis());
		System.out.println("Milliseconds in 150 minutes = "+d3.toMillis());
	}
}