🚀 go-pugleaf

I'm just starting out learning Java and am having problems with my Linux
Java compiler.  The first time it worked with the simple javascript that
I wrote.  I've tried to write two others and neither of the others will
run.  It compiles it but will not run them.

Here's the ones I wrote:

Big Debt.java  (This one worked the first time):

class BigDebt {
    public static void main (String arguments[]) {
        int debt = 59000000;
       debt = debt / 86400;
        System.out.println("A second's worth of debt is $" + debt);
    }
}


Root.java:

 class Root {
         public static void main(String[] arguments) {
                 int number = 225;
                 System.out.println("The square root of "
                         + number
                         + " is "
                         + Math.sqrt(number) );
         }
 }


Hello World.java:

class HelloWorld {
     public static void main (String args[]) {
         System.out.println("Hello World!");
     }
 }

**********************************************

After compiling them and try to run the resulting   .class   program, I
get the following error:

Exception in thread "main" java.lang.NoClassDefFoundError:
HelloWorld/java