A solid disc of radius \( 20 \, \text{cm} \) and mass \( 10 \, \text{kg} \) is rotating with an angular velocity of \( 600 \, \text{rpm} \), about an axis normal to its circular plane and passing through its centre of mass. The retarding torque required to bring the disc at rest in \( 10 \, \text{s} \) is __________ \( \pi \times 10^{-1} \, \text{Nm} \).
