Răspuns: 8
[tex]\dfrac{2}{7} \cdot \Big [\dfrac{2}{7} \cdot \Big( \dfrac{2}{7}\cdot343 \Big ) \Big ]=\\\\\\ \dfrac{2}{7} \cdot \Big [\dfrac{2}{7} \cdot ( 2\cdot49 ) \Big ]=\\\\\\ \dfrac{2}{7} \cdot \Big (\dfrac{2}{7} \cdot 98 \Big )=\\\\\\\dfrac{2}{7} \cdot 2 \cdot 14=\\\\\\2\cdot2\cdot2=\\\\\\\boxed{8}[/tex]