Two meshing spur gears $1$ and $2$ with diametral pitch of $8$ teeth per mm and an angular velocity ratio $\left|\omega_{2}\right| /\left|\omega_{1}\right|=1 / 4$, have their centers $30 \mathrm{~mm}$ apart. The number of teeth on the driver (gear $1$) is___________.
(Answer in integer)
