5 mg = __________  kg

$5\text{mg\hspace{0.17em}}=5\times {10}^{-3}\text{g }\because 1\text{mg\hspace{0.17em}}={10}^{-3}\text{g}$

$=5\times {10}^{-3}\times {10}^{-3}\text{kg }1\text{g\hspace{0.17em}}={10}^{-3}\text{kg}$

$=5\times {10}^{-6}\text{kg}$

$\therefore 5\text{mg\hspace{0.17em}}=5\times {10}^{-6}\text{kg}$