Explain : "By using significant digit we can prevent unnecessary long calculation.

Explanation

In significant number with increase in number of significant digit accuracy increase.
Measurement of physical quantity involves addition, subtraction, multiplication and division which result into more number of significant digit.
Result of calculation should be in consistency of input value of measurement.
For example, mass of object is m = 4.237 g and volume `V = 2.52 cm^(3)`
Then density
`rho=(m)/(V)`
`:. rho=(4.237)/(2.51)`
`=1.68804780876 g cm^(-3)`
Which is unnecessary long. Hence, it should be round off. Hence, practical value of density will be `1.69 g cm^(-3)`