${\left(\frac{2}{3}\right)}^2=\frac{2}{3}\cdot \frac{2}{3}=\frac{4}{9}$

${\left(\frac{1}{4}\right)}^3=\frac{1}{4}\cdot \frac{1}{4}\cdot \frac{1}{4}=\frac{1}{16}\cdot \frac{1}{4}=\frac{1}{64}$

${\left(1\frac{1}{2}\right)}^3={\left(\frac{3}{2}\right)}^3=\frac{3}{2}\cdot \frac{3}{2}\cdot \frac{3}{2}=$ $\frac{9}{4}\cdot \frac{3}{2}=\frac{27}{8}=3\frac{3}{8}$

${\left(2\frac{2}{5}\right)}^2={\left(\frac{12}{5}\right)}^2=\frac{12}{5}\cdot \frac{12}{5}=\frac{144}{25}=5\frac{19}{25}$