One main scale division of a vernier caliper is equal to \( m \) units. If \( n^{\text{th}} \) division of main scale coincides with \( (n+1)^{\text{th}} \) division of vernier scale, the least count of the vernier caliper is:
\( \frac{m}{n(n+1)} \)
\( \frac{1}{(n+1)} \)
\( \frac{m}{(n+1)} \)
\( \frac{n}{(n+1)} \)