\[\boxed{\mathbf{2.}\mathbf{402}}\]
\[\textbf{а)}\ \left( \frac{1}{3} \right)^{3} = \frac{1}{3} \cdot \frac{1}{3} \cdot \frac{1}{3} = \frac{1}{27}\]
\[\textbf{б)}\ \left( \frac{1}{2} \right)^{3} + \frac{1^{\backslash 2}}{4} = \frac{1}{8} + \frac{2}{8} = \frac{3}{8}\]
\[\textbf{в)}\ \left( 1 - \frac{4}{5} \right)^{3} = \left( \frac{1}{5} \right)^{3} = \frac{1}{5} \cdot \frac{1}{5} \cdot \frac{1}{5} =\]
\[= \frac{1}{125}\]