Two circular coils $P$ and $Q$ of 100 turns each have same radius of $\pi$ cm. The currents in $P$ and $Q$ are 1 A and 2 A respectively. $P$ and $Q$ are placed with their planes mutually perpendicular with their centers coincide. The resultant magnetic field induction at the center of the coils is $\sqrt{x}$ mT, where $x =$ $\_\_\_\_$. [Use $\mu_0 = 4\pi \times 10^{-7}$ T m A$^{-1}$]