Write about significant figures.

(N/A) Significant figures are meaningful digits in a measured or calculated quantity. The rules for determining them are as follows:
$(i)$ All non-zero digits are significant. For example,in $285 \ cm$,there are $3$ significant figures,and in $0.25 \ mL$,there are $2$ significant figures.
$(ii)$ Zeros preceding the first non-zero digit are not significant. They only indicate the position of the decimal point. Thus,$0.03$ has $1$ significant figure and $0.0052$ has $2$ significant figures.
$(iii)$ Zeros between two non-zero digits are significant. Thus,$2.005$ has $4$ significant figures.
$(iv)$ Zeros at the end or to the right of a number are significant if they are on the right side of the decimal point. For example,$0.200 \ g$ has $3$ significant figures. However,terminal zeros are not significant if there is no decimal point. For example,$100$ has only $1$ significant figure.
$(v)$ Exact numbers,such as $2$ balls or $20$ eggs,have an infinite number of significant figures because they can be represented as $2.0000...$ or $20.0000...$.
Addition and Subtraction: The result should have the same number of decimal places as the measurement with the fewest decimal places. For example,$12.11 + 18.0 + 1.012 = 31.122$,which is rounded to $31.1$ because $18.0$ has only one decimal place.
Multiplication and Division: The result should have the same number of significant figures as the measurement with the fewest significant figures. For example,$2.5 \times 1.25 = 3.125$,which is rounded to $3.1$ because $2.5$ has only $2$ significant figures.