how to rationalise a given irrational number?

Dear student
It is done by Rationalising the denominator.
$$\begin{gathered} \mathrm{Consider} \mathrm{the} \mathrm{irrational} \mathrm{number} \frac{1}{\sqrt{3}} \\ \mathrm{To} \mathrm{rationalise} \mathrm{it} \mathrm{we} \mathrm{will} \mathrm{multiply} \mathrm{and} \mathrm{divide} \mathrm{by} \sqrt{3} \\ \mathrm{i}.\mathrm{e}. \frac{1}{\sqrt{3}}\times \frac{\sqrt{3}}{\sqrt{3}}=\frac{\sqrt{3}}{3} \end{gathered}$$
Regards