import java.io.InputStreamReader;
import java.text.DecimalFormat;
import java.util.Scanner;

public class Reverse {

    private static void printer(double value){
        String pattern = "###0.0000";
        DecimalFormat myFormatter = new DecimalFormat(pattern);
        String output = myFormatter.format(value);
        System.out.println(output);
    }
    public static void main(String[] args) {
        Scanner sc = new Scanner(new InputStreamReader(System.in));
        long a,b,c,d;

        a = sc.nextLong();
        b = sc.nextLong();
        c = sc.nextLong();
        d = sc.nextLong();

        printer(Math.sqrt(d));
        printer(Math.sqrt(c));
        printer(Math.sqrt(b));
        printer(Math.sqrt(a));
    }
}

In your solution, it is possible just 4 numbers (a,b,c,d).

Suggestion: try using a loop instead of a,b,c,d and finish the loop when the user type something different than a number