2.005
16.3
6.71 is 6.7050 is rounded to three significant figures.
0.00185
31.5
2.005
16.3
6.71 is 6.7050 is rounded to three significant figures.
0.00185
31.5
It is 307 cm.
323.565 rounded to three significant digits is 323.56
0.00909 has three significant digits.
Three significant digits.
There are three significant digits in 3.56.
It isn't clear what the question is. If you are supposed to multiply or divide, and if by "signification figures" you mean significant digits, do the multiplication (or division), then round to three significant digits - since the least-precise of the numbers only has three significant digits.
Three - zeros between significant digits are significant.