For the determination of refractive index of glass slab, a travelling microscope is used whose main scale contains \( 300 \) equal divisions equals to \( 15 \,\text{cm} \). The vernier scale attached to the microscope has \( 25 \) divisions equals to \( 24 \) divisions of main scale.
The least count (\( LC \)) of the travelling microscope is (in \( \text{cm} \)):