Two.
Two.
Two.
Two.
231.57 has five significant figures/numbers. All the numbers in 231.57 are significant.
13 has two significant figures.
The figure 18.03 has a total of four significant numbers
26
4 All of them are significant. Only zeros are potentially insignificant. And that's only when your numbers either start with zeros like 0.001 (1 significant digit 1) or end with zeros 13.0000 (2 significant digit, 13). Any zeros between non-zero numbers are significant.
Because 10.00400 is 10.004, this has five significant digits (numbers).
Three. All nonzero numbers are significant, and any zeros in between significant numbers are significant.
There are 5 significant figures.
1 significant figure.
5 significant figures.
Three significant figures.
Four significant figures.