Explain: "By using significant digits,we can prevent unnecessarily long calculations."

(N/A) $1$. In significant figures,as the number of significant digits increases,the precision of the measurement increases.
$2$. Mathematical operations like addition,subtraction,multiplication,and division on measured physical quantities often result in a large number of decimal places.
$3$. The final result of a calculation should be consistent with the precision of the input measurements.
$4$. For example,if the mass of an object is $m = 4.237 \ g$ and its volume is $V = 2.51 \ cm^{3}$,then the density $\rho$ is calculated as:
$\rho = \frac{m}{V} = \frac{4.237}{2.51} = 1.68804780876 \ g \ cm^{-3}$.
$5$. This result is unnecessarily long. According to the rules of significant figures,the result should be rounded off to the same number of significant digits as the least precise measurement (which is $3$ in this case). Thus,the practical value of density is $1.69 \ g \ cm^{-3}$.