Four
231.57 has five significant figures/numbers. All the numbers in 231.57 are significant.
3 significant figures.
2310 has 3 significant figures.
Five
6
Three of them which are 528
It is 5280
Three. The last zero is just a placeholder.
5280
13, or any number greater than 5280.
Three significant figures. A significant figure is any non-zero digit or any embedded or trailing zero. Leading zeros are not significant.
231.57 has five significant figures/numbers. All the numbers in 231.57 are significant.
There are exactly 5280 feet in each mile. In 82,341 feet therefore are 82,341/5280 = 15.595 miles, to the justified number of significant digits.
In the entire infinite supply of whole numbers, fractions, and decimals, whether positive or negative, there is only one single number that is equal to 5280. It is . . . . . 5280 .
The figure 18.03 has a total of four significant numbers
5280 + 5280 + (¾ x 5280)...
Three. All nonzero numbers are significant, and any zeros in between significant numbers are significant.