\[\boxed{\mathbf{2.2}\mathbf{73}}\]
Пояснение.
Решение.
\[V = a^{3};\ \ \ a = \frac{5}{8}\ дм.\]
\[V = \left( \frac{5}{8} \right)^{3} = \frac{5}{8} \cdot \frac{5}{8} \cdot \frac{5}{8} = \frac{5 \cdot 5 \cdot 5}{8 \cdot 8 \cdot 8} =\]
\[= \frac{125}{512}\ \left( дм^{3} \right).\]
\[Ответ:\ \frac{125}{512}\ дм^{3}.\]