<P> Least count uncertainty is one of the sources of experimental error in measurements . </P> <P> The smallest value that can be measured by the measuring instrument is called its least count . Measured values are good only up to this value . The least count error is the error associated with the resolution of the instrument . </P> <P> If we use a metre scale for measurement of length, it may have graduations at 1 mm division scale spacing or interval . A Vernier scale on caliper may have a least count of 0.02 mm while a micrometer have least count of 0.001 mm . </P> <P> The least count error occurs with both systematic and random errors . Instruments of higher precision can reduce the least count error . By repeating the observations and taking the arithmetic mean of the result, the mean value would be very close to the true value of the measured quantity . </P>

Least count of vernier caliper and screw gauge