^Least count, accuracy & significant digits

^Least count, accuracy & significant digits

Suppose a rod is measured by a metre stick, and is estimated to lie between 1.6 and 1.8 m, then its length can be written as 1.7 m. It contains two significant digits, of which we are perfectly sure of the position of 1, but slightly doubtful regarding the position of 7.

Now, suppose the same rod is measured by a metre scale graduated to centimetres and is estimated to lie between 173.2 cm & 173.4 cm then its length can be written as 173.3 cm or 1.733 m. Now, the number of significant digits are four namely, 1, 7, 3 and 3 and hence there is an increment in the accuracy of the value. Smaller the least count of a measuring instrument, more will be its accuracy in measurement and accordingly more will be the number of significant digits.