Three.
8
It is: 12.66 cm
The zero is not counted in the significant digits. It only indicates the accuracy. To count significant don't count zeroes unless it between other non-zeroes.
0.00185
Three.
8
The number 48 cm has two significant digits. The leading 0 is not significant in this case.
Two of them.
It is: 12.66 cm
1.004 cm
It is 307 cm.
Yes.
38 cm
(152 cm/(2.54 cm/in)/(12.0 in/ft) = 4.99 feet, to the justified number of significant digits.
The zero is not counted in the significant digits. It only indicates the accuracy. To count significant don't count zeroes unless it between other non-zeroes.
Two, the number of significant digits in the least precisely stated datum, 2.5 cm.