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We
use measurements of different types in our daily life. For
example, while buying cloth, we measure its length and while
buying milk or kerosene we measure its volume. But for accurate
and precise measurement, we have to follow certain methods.
Let us study some of them.
Let us consider a physical quantity, say length. We know that
its standard of measurement is metre. Measuring sticks with
the same length as the standard metre have been made which
we commonly call as the metre stick. This one metre long stick
is divided into 100 equal parts, i.e. into 100 centimetres.
Each centimetre is further divided into 10 millimetres. Thus,
the smallest division on a metre scale is 1 millimetre. This
is the least count of the metre scale. Thus, the minimum or
the least quantity that can be measured by a given instrument
is called its least count. For example, the least count of
a metre scale is 1 mm or 0.1 cm. A metre scale cannot measure
lengths less than 1mm. The least count of any measuring instrument
is, thus, very important. We must always quote the result
of a measurement only up to the least count of the measuring
instrument used. Besides, the method and the selection of
proper measuring device for a particular measurement are also
very important.
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