Java Classwork #6 (SimpleCalculator)
06) Create a non-static class named 'SimpleCalculator' in its own file.  The
    class should contain a single constructor and should perform addition and
    multiplication of sets of two and three numbers of type double.  When the
    following sample 'main' code is run, it should produce the exact output
    shown below:
    
    SAMPLE CALLING CODE:
        public static void main(String[] args)
        {
           SimpleCalculator calc = new SimpleCalculator();

           calc.add(3.5, 4.2);
           calc.add(2.45, 7.1, 3.6);

           System.out.println();

           calc.multiply(1.9, 8.4);
           calc.multiply(3.8, 2.57, 4.6);
        }

    EXACT OUTPUT FROM ABOVE CODE:
        The sum of 3.5 and 4.2 is 7.70.
        The sum of 2.45 and 7.1 and 3.6 is 13.15.

        The product of 1.9 and 8.4 is 15.96.
        The product of 3.8 and 2.57 and 4.6 is 44.92.
    
    You must use the 'printf' method to display all answers (sums and products)
    rounded to exactly two decimal places.  (Do not change the manner in which
    user-supplied numbers are displayed.)

    The above sample calling code is merely an example.  Your 'SimpleCalculator'
    class should be able to add and multiply ANY two-number and three-number
    combinations.  Also, remember that the method 'main' and the keyword
    'static' must not appear anywhere in the 'SimpleCalculator' class.


ADVANCED OPTION #1 FOR CLASSWORK #6
    To the 'SimpleCalculator' class, add two more public methods, named
    'addUnlimited' and 'multiplyUnlimited', both of which allow an unlimited
    number of arguments of type double.  These two new methods do not need to
    display the arguments back to the user.  They do, of course, need to
    display the calculated answers.  Note that you may complete the other
    advanced options in addition to, or instead of, this option.

ADVANCED OPTION #2 FOR CLASSWORK #6
    To the 'SimpleCalculator' class, add two more public methods, named
    'subtract' and 'divide'.  The 'subtract' method should take two
    arguments (doubles) and display the result when the second number is
    subtracted from the first number.  Display the result in the same
    manner that the 'add' and 'multiply' methods display their results.
    The 'divide' method should work in the same manner as the 'subtract'
    method, except that the two numbers should be divided.  However,
    if the second number is zero, then display a statement indicating
    that a number cannot be divided by zero.  Note that you may complete
    this advanced option in addition to, or instead of, either of the
    other options.

ADVANCED OPTION #3 FOR CLASSWORK #6
    To the 'SimpleCalculator' class, add additional methods of your
    choosing.  For example, you might add a 'power' method that takes
    two integer arguments and then raises the first integer to the
    power of the second (e.g., power(2, 5) displays 32).  Or, you might
    add a method named 'squareRoot' which displays the square root of a
    number.  These are just examples, and you should consider adding
    other methods of your choosing.  For each method that you add, also
    add code to the constructor that displays a message (whenever a
    'SimpleCalculator' object is created) that tells the user what
    methods are available in your calculator.  Be sure to include in
    the message the required methods, as well as any additional methods
    that you added for the above extra credit options.  Note that you
    may complete this advanced option in addition to, or instead of,
    any of the above options.