4 of them.
231.57 has five significant figures/numbers. All the numbers in 231.57 are significant.
The figure 18.03 has a total of four significant numbers
3.6 miles per 5797m
3 significant figures.
3 significant figures.
2 significant figures.
It has five significant figures.
4 significant figures
3 significant figures.
7 significant figures.
2 significant figures.