How do you get the least count of a Vernier caliper with the following information?

I have a caliper with 10 as the total number of vernier divisions. For the main scale, the reading just before the vernier zero mark is 12 mm, while the reading after the vernier zero mark is 13 mm. The number of vernier divisions that coincide with the main scale division is 6. Do I solve it by subtracting 6 from 12, then dividing the answer with 10? Your help is greatly appreciated.