$a)34093=3\cdot {10}^4+4\cdot {10}^3+0\cdot {10}^2+9\cdot {10}^1+3\cdot {10}^0$  

$b)45000371=4\cdot {10}^7+5\cdot {10}^6+0\cdot {10}^5+0\cdot {10}^4+0\cdot {10}^3++3\cdot {10}^2+7\cdot {10}^1+1\cdot {10}^0$  

$c)4,07=4\cdot {10}^0+0\cdot {10}^{-1}+7\cdot {10}^{-2}$   

$d)0,3208=3\cdot {10}^{-1}+2\cdot {10}^{-2}+0\cdot {10}^{-3}+8\cdot {10}^{-4}$