Variable-length argument lists can be used to create methods that receive an unspecified number of arguments.

In this statement, public static double mchee (double...num), it means that variable number of double (data type) values can be passed to this method.

The condition that parameter type followed by an ellipsis can occur a few times at the end of a parameter list.

Parameter type followed by an ellipsis indicates that the method receives a variable number of arguments of that particular type.

Ellipsis is represented by this syntax (...) in Java programming.