[tex]Bonjour; \\\\\\ \dfrac{2,1\times10^4 \times 20 \times (10^{-2})^3}{0,7\times 10^{-8}} = \dfrac{2,1\times20 }{0,7} \times \dfrac{10^4 \times 10^{-6}}{10^{-8}} \\\\\\ = 60 \times 10^{4 - 6 + 8} = 60 \times 10^6 = 6 \times 10^7 = 60 000 000 \ .[/tex]