Given $$\sqrt 5 = 2.2361,$$   $$\sqrt 3 = 1.7321{\text{,}}$$   then $$\frac{1}{{\sqrt 5 - \sqrt 3 }}$$   is equal to ?

$$\eqalign{ & \Rightarrow \frac{1}{{\sqrt 5 - \sqrt 3 }} \cr & = \frac{1}{{\sqrt 5 - \sqrt 3 }} \times \frac{{\left( {\sqrt 5 + \sqrt 3 } \right)}}{{\left( {\sqrt 5 + \sqrt 3 } \right)}} \cr & = \frac{{\left( {\sqrt 5 + \sqrt 3 } \right)}}{{5 - 3}} \cr & = \frac{{\left( {2.2361 + 1.7321} \right)}}{2} \cr & = \frac{{3.9682}}{2} \cr & = 1.9841{\text{ }} \cr} $$