The smallest division on main scale of a vernier callipers is $1 \mathrm{mm}$ and 10 vernier divisions coincide with 9 main scale divisions. While measuring the length of a line, the zero mark of the vernier scale lies between $10.2 \mathrm{cm}$ and $10.3 \mathrm{cm}$ and the third division of vernier scale coincides with a main scale division. Determine the least count of the callipers.