2
0.00075kg is 750mg
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
Three. All nonzero numbers are significant, and any zeros in between significant numbers are significant.
Assuming you mean percent of 100. It is .00075%
Because 10.00400 is 10.004, this has five significant digits (numbers).
There are 5 significant figures.
It has 4 significant figures
Four significant figures.
Three significant figures.
5 significant figures.
Four significant figures.