a = \frac{10^{- 3} N}{4, 5 \cdot 10^{- 4} k g} = \underline{\underline{2 m s^{- 2}}}

${a = \frac{10^{-3}\, \mathrm{N}}{4,5 \cdot 10^{-4}\, \mathrm{kg}} = \underline{\underline{2\, \mathrm{ms^{-2}}}}}$

Error