Keeping the significant figures in view,the sum of the physical quantities $52.01 \ m$,$153.2 \ m$,and $0.123 \ m$ is: (in $m$)

The result after adding $3.8 \times 10^{-6}$ and $4.2 \times 10^{-5}$ with due regard to significant figures is:

What are significant figures? What are significant digits? Explain with examples.

The number of significant figures in $200.40$ is

Statement-$1$: All reliable digits plus the first uncertain digit together are called significant figures.
Statement-$2$: Trailing zero$(s)$ in a number with a decimal point are never significant.

From the point of view of significant figures,which of the following is/are correct?
$(i)\ 11.3 \ cm + 4 \ cm = 15.3 \ cm$
$(ii)\ 4.53 \ m - 1.2 \ m = 3.3 \ m$
$(iii)\ 5.45 \ kg - 3.2 \ kg = 2.25 \ kg$
$(iv)\ 84.8 \ cm + 48.6 \ cm = 133 \ cm$