$(\sqrt{6}{)}^2=6$

$(-<!--\; -\; -->\sqrt{21}{)}^2=(-<!--\; -\; -->1{)}^2\ast <!--\; \ast \; -->(\sqrt{21}{)}^2=1\ast <!--\; \ast \; -->21=21$

$(3\sqrt{2}{)}^2=3^2\ast <!--\; \ast \; -->(\sqrt{2}{)}^2=9\ast <!--\; \ast \; -->2=18$

$(-<!--\; -\; -->4\sqrt{5}{)}^2=(-<!--\; -\; -->4{)}^2\ast <!--\; \ast \; -->(\sqrt{5}{)}^2=16\ast <!--\; \ast \; -->5=80$

$(-<!--\; -\; -->\frac{\sqrt{6}}{3}{)}^2=(-<!--\; -\; -->1{)}^2\ast <!--\; \ast \; -->\frac{(\sqrt{6}{)}^2}{3^2}=1\ast <!--\; \ast \; -->\frac{6}{9}=\frac{2}{3}$

$(\frac{1}{4}\sqrt{26}{)}^2=(\frac{1}{4}{)}^2\ast <!--\; \ast \; -->(\sqrt{26}{)}^2=\frac{1}{16}\ast <!--\; \ast \; -->26=\frac{13}{8}=1\frac{5}{8}$