A projectile is fired from horizontal ground  with speed v and projection angle $\mathrm{\theta }$. When the acceleration due to gravity is g, the range of the projectile is d. If at the highest point in its trajectory, the projectile enters a different region where the effective acceleration due to gravity is ${\mathrm{g}}^{\mathrm{\prime }}=\frac{\mathrm{g}}{0.81}$ then the new range is d¹ = nd. The value of n is _______