$\mathrm{CO}_2$ gas adsorbs on charcoal following Freundlich adsorption isotherm. For a given amount of charcoal, the mass of $\mathrm{CO}_2$ adsorbed becomes 64 times when the pressure of $\mathrm{CO}_2$ is doubled. The value of n in the Freundlich isotherm equation is $\_\_\_\_$ $\times 10^{-2}$. (Round off to the Nearest Integer)