Least count of a measuring instrument is the least value of physical quantity that can be measured accurately using the instrument.
Consider a spring balance whose range is 0-25kg.
In its scale, you can see that the 1kg is divided into 10 equal parts. Therefore, the least value it can measure is 100g which can be found out by,
Measurement =1kg
Number of divisions = 10
Least count =1/10 = 0.1kg or 100g
100g is the least count of the spring balance. Similarly we can find the least count of different spring balances of different range.
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