A vernier callipers has its main scale graduated in mm and 10 divisions on its vernier scale are equal in length to 9 mm. When the two jaws are in contact, the zero of vernier scale is ahead of zero of main scale and 3rd division of vernier scale coincides with a main scale division. Find the least count .

Explanation

To find the least count of the vernier calipers, we can follow these steps:

### Step 1: Understand the scales
The main scale of the vernier calipers is graduated in millimeters (mm). This means that each division on the main scale represents 1 mm.

### Step 2: Determine the length of the vernier scale divisions
We know that 10 divisions on the vernier scale are equal to 9 mm. Therefore, we can calculate the length of one division on the vernier scale.

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