Just the one
3 sig figs
4 sig figs the ending zero is not significant unless it was a measurement and the zero was an estimation that was part of the measurement.
Three of them
3 sig figs.
1080
there are 3 sig figs. 4, 0, and 5 are the sig figs
5 sig figs
61 has 2 sig figs.
There are five sig figs
There are four sig figs in 2.905.
There are three sig figs in 1.05.
There are three sig figs in 4890.
All five of them are sig figs
There are two sig figs in 3700000.
There are two sig figs in 290.
There are five sig figs in 4.1275.
6.002 has four sig figs.