A hollow cylindrical conductor has length of $3.14 \mathrm{m}$, while its inner and outer diameters are $4 \mathrm{mm}$ and $8 \mathrm{mm}$ respectively. The resistance of the conductor is $\mathrm{n}\times {10}^{-3} \Omega$.
If the resistivity of the material is $2.4\times {10}^{-8} \Omega \mathrm{m}$. The value of $\mathrm{n}$ is _____.