5 significant figures.
there are 2 significant figures
There are four significant figures in 34.80 km.
There are 6 significant figures
3 of them.
2
It is the digit 2
3 of them.
The distance measurement of 20.070 km has five significant figures. This includes the digits 2, 0, 0, 7, and the final 0, which is significant because it is to the right of the decimal point. Leading zeros are not significant, but trailing zeros in a decimal measurement are considered significant.
3.774 is to 4 significant figures (count them)
1,000 m = 1 km If there is not decimal point at the end of 1000. it is just 1km. If there is a decimal point the correct significant figures would be 1.000 km
Assuming the final zero is not there for decorative purposes, 6 sig figs.
All of those figures are significant. If you want to round it to 2 sig figs, that would be 13.