How can I prove that {$p$} is a nullset? In measure theory, I don't have any idea to show that for 
$p \in \mathbb{R^n}$ the set  {$p$} is a null set.
Can somebody give me any hint about this? 

Let $I_\varepsilon=\left]p_1-\frac{\sqrt[n]\varepsilon}{2},p_1+\frac{\sqrt[n]\varepsilon}{2}\right[\times ...\times \left]p_n-\frac{\sqrt[n]\varepsilon}{2},p_n+\frac{\sqrt[n]\varepsilon}{2}\right[$. For all $\varepsilon>0$,
$$m(\{p\})< m(I_\varepsilon)=\varepsilon,$$
what prove the claim.
