Question

What is the least count of galvanometer and ammeter ?how will we able to find it ?​

Answer 1

Least count of a measuring instrument is the least value of physical quantity that can be measured accurately using the instrument.

Answer 2

There is no least count to a galvanometer since it does not depict any quantity, while that of ammeter differs with different ranged devices.
Actually least count is the smallest value that can be measured accurately by a device.
Least count = maximum value of quantity/number of divisions.........