Eliminating the radicals from the denominator of a fraction makes it simpler to compute an approximation.
This algebraic process is called rationalization or root rationalization.
For instance,
$
\frac{2}{\sqrt{3}} = \frac{2}{\sqrt{3}} \cdot \frac{\sqrt{3}}{\sqrt{3}} = \frac{2 \sqrt{3}}{3}
$