http://www.matheboard.de/kgv_ggt_mehrere_zahlen.php
http://jumk.de/formeln/kgv.shtml
$${\sqrt{{\mathtt{16}}}} = {\mathtt{4}}$$
$${\sqrt{{\sqrt{{\mathtt{16}}}}}} = {\mathtt{2}}$$
$${\sqrt{{\mathtt{2}}}} = {\mathtt{1.414\: \!213\: \!562\: \!373\: \!095}}$$ ; $${{\mathtt{16}}}^{\left({\frac{{\mathtt{1}}}{{\mathtt{8}}}}\right)} = {\mathtt{1.414\: \!213\: \!562\: \!373\: \!095}}$$
$${\sqrt[{{\mathtt{3}}}]{{\mathtt{27}}}} = {\mathtt{3}}$$ ; $${\sqrt[{{\mathtt{27}}}]{{\mathtt{27}}}} = {\mathtt{1.129\: \!830\: \!963\: \!909\: \!753}}$$ ; $${\sqrt[{{\mathtt{9}}}]{{\mathtt{27}}}} = {\mathtt{1.442\: \!249\: \!570\: \!307\: \!408\: \!4}}$$
$${\sqrt[{{\mathtt{8}}}]{{\mathtt{27}}}} = {\mathtt{1.509\: \!803\: \!648\: \!477\: \!105}}$$ ; $${\sqrt[{{\mathtt{4}}}]{{\mathtt{27}}}} = {\mathtt{2.279\: \!507\: \!056\: \!954\: \!777\: \!6}}$$
http://www.frustfrei-lernen.de/mathematik/wurzel-dritte-vierte.html