Yes.
It is 307 cm.
Three.
0.00185
Two - all nonzero numbers are significant.
It is: 12.66 cm
1.004 cm
38 cm
4
8
This has 4 significant figures, and they are 6420
Four: All the digits given are significant.>> Two actually. Trailing zeros in a number without a dp are not significant unless emphasised in some way. The unit (mm) doesn't make any difference.
The measurement of 29.46 cm when rounded to three significant numbers becomes 29.5 cm