The number 0.0102030 has 6 significant figures. Each of the non-zero numerals (3 of those), the zeros between the non-zero numbers (2), and the zero on the end of the number if it is right of the decimal (1). The significant figures are in bold:
0.0102030
6
There are two significant figures in the measurement 0.0039.
There are four significant figures in the measurement 1.050 L.
There are three. The 4, the 5 and the zero in between. The two last zeros serve only to properly space the decimal point which, in this number, is implied.
There are three significant figures in 43.0. The zero at the end of the number is considered significant because it serves to specify the accuracy of the measurement to the tenths place.
There are 4 significant figures in this measurement.
There are 3 significant figures in this measurement.
There are 3 significant figures in this measurement.
There are 2 significant figures in this measurement.
There are 2 significant figures in this measurement.
There are 2 significant figures in this measurement.
There are 3 significant figures in this measurement.
There are 2 significant figures in this measurement.
There are 2 significant figures in this measurement.
There are 5 significant figures in this measurement.
There are 3 significant figures in this measurement.
There are 2 significant figures in this measurement.