5 significant figures.
2 of them.
12.655 cm rounded to four significant figures is 12.66cm
Four.
All three of them are significant figures
102.3 cm
How many significant figures are in the measurement 210 cm?
There are 4 significant figures in this number.
There are 2 significant figures in this measurement.
4.05 has three (3) significant figures
There are 3 significant figures
None. The abbreviation cm represents one or more centimeters. In your question there are no numbers associated with the cm unit, therefore there are no significant figures.
2 of them.
12.655 cm rounded to four significant figures is 12.66cm
This has 4 significant figures, and they are 6420
3 of them.
Four.
It has 2 significant figures. However, the fact that it is given as 2300 mm and not as 230 cm suggests that it is, in fact significant to 4 figures.