Least count of a vernier caliper is \(\displaystyle \frac{1}{20N} \) cm. The value of one division on the main scale is \( 1 \, \text{mm} \). Then the number of divisions of main scale that coincide with \( N \) division of vernier scale is:
\( \displaystyle \left(\frac{2N-1}{20N} \right) \)
\(\displaystyle (2N-1 )\)
\(\displaystyle \left(\frac{2N-1}{2N} \right) \)
\(\displaystyle \left(\frac{2N-1}{2} \right) \)