13. A cube with an edge length of 0.5 m is cut into cubes, each with an edge length of 2 mm. The resulting cubes are laid out in a single continuous row. What is the length of this row
13. $0.5 \text{m} = 500$ mm. The volume of the given cube is $500 \cdot 500 \cdot 500 \text{m}^{3}$, the volume of each cube obtained after cutting is $2 \cdot 2 \cdot 2 \text{mm}^{3}$. As a result of cutting, the number of cubes obtained is $(500 \cdot 500 \cdot 500):(2 \cdot 2 \cdot 2)=15625000$. Therefore, the length of the row will be $2 \text{mm} \cdot 15625000=31$ km $250 \text{m}$.