import java.time.Duration;
import java.time.Instant;
 
public class Main {
	public static void main(String[] args) {
		// A sample date-time in the past
		String strDateTime = "2020-09-10T10:20:30.123456789Z";
 
		Instant past = Instant.parse(strDateTime);
		Instant now = Instant.now();
 
		Duration duration = Duration.between(past, now);
		long durationInMillis = duration.toMillis();
 
		double days = (double) durationInMillis / Duration.ofDays(1).toMillis();
		System.out.println(days);
	}
}

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