2
Two. The zeros are just placeholders.
There are 1609.344 metres in one mile. Therefore, 93000000 miles is equal to 93000000 x 1609.344 = 149668992000 metres.
231.57 has five significant figures/numbers. All the numbers in 231.57 are significant.
One
It is 93000000
The figure 18.03 has a total of four significant numbers
Three. All nonzero numbers are significant, and any zeros in between significant numbers are significant.
3 significant figures.
3 significant figures.
2 significant figures.
It has five significant figures.