(1000)^2/3
Thanks Radix,
OR
$$1000^{2/3}=(1000^{1/3})^2=(\sqrt[3]{1000})^2=10^2=100$$
$${{\mathtt{1\,000}}}^{\left({\frac{{\mathtt{2}}}{{\mathtt{3}}}}\right)}$$ = $${\sqrt[{{\mathtt{{\mathtt{3}}}}}]{{{\mathtt{1\,000}}}^{{\mathtt{2}}}}} = {\mathtt{100}}$$
$${\sqrt[{{\mathtt{{\mathtt{3}}}}}]{{\mathtt{1\,000\,000}}}} = {\mathtt{100}}$$