how to find the lest count of the ammeter and voltmeter?
Least count of a measuring instrument is the least value of physical quantity that can be measured accurately using the instrument.
For example, Take a simple scale (length measuring instrument) of 15 cm. In this scale, you can see that the 1 cm is divided into 10 equal parts. Therefore, the least value it can measure is 1cm/10=0.1cm or 1mm which is least count of this instrument.