Answer: There are six.
Answer: There is no such thing as "significant numbers". I assume you mean "significant digits". All digits are significant in this case - a zero (or more than one zero) between other digits is always significant.
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.
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.
1 significant figure.
3 significant figures.