Answer
$10$
Work Step by Step
Using $a^{m/n}=\sqrt[n]{a^m}=(\sqrt[n]{a})^m$, the given expression, $
100^{1/2}
,$ is equivalent to
\begin{array}{l}\require{cancel}
\sqrt[]{100^1}
\\\\=
\sqrt[]{100}
\\\\=
\sqrt[]{(10)^2}
\\\\=
10
.\end{array}