The mass of a building is 3000 metric ton and mass of a apartment is 4500 metric ton. If the distance between them is 1 km. Calculate the force exerted by building on apartment.

Mass of a building is 3 x 10⁶ kg (m₁)
Mass of a apartment is 4.5 x 10⁶ kg (m₂)
distance between them is 1000 m (d)
G =  6.673 x 10⁻¹¹ Nm²kg⁻²

$$\begin{gathered} \mathrm{F}=\frac{{\mathrm{Gm}}_1{\mathrm{m}}_2}{{\mathrm{d}}^2} \mathrm{F}=\frac{{\mathrm{Gm}}_1{\mathrm{m}}_2}{{\mathrm{d}}^2} \\ \mathrm{F}=\frac{6.673\times {10}^{-11}\times (3\times {10}^6)(4.5\times {10}^6)\times 100}{{1000}^2} \\ \mathrm{F}=\frac{90.08\times {10}^{(-11+12)}}{1\times {10}^6} \\ \mathrm{F}=90.08\times {10}^{-5} \end{gathered}$$