Q:  What is the radius of a black hole with a mass equal to the Sun?
             (M = 1.99 x 10^(30) kg)

                        2 * 6.67 x 10^(-11) N*m^2/kg^2 * 1.99 x 10^(30) kg
           R  =  sqrt( ---------------------------------------------------- )
                                  [ 3 x 10^(8) m/s ]^2


              =   2950 meters  ~=   3 km



  Q:  What is the radius of a black hole with a mass equal to the Earth?
             (M = 5.98 x 10^(24) kg)


                        2 * 6.67 x 10^(-11) N*m^2/kg^2 * 5.98 x 10^(24) kg
           R  =  sqrt( ---------------------------------------------------- )
                                  [ 3 x 10^(8) m/s ]^2


              =   0.0089 meters  ~=  9 mm