There are 3 significant figures in this measurement.
3 of them.
2
3
3 of them.
52.8005 mg to five significant figures is 52.801 mg.
2 significant figures.
There are 3 significant figures in this measurement.
There are 2 significant figures in this measurement.
There are 3 significant figures in this measurement.
4
3 of them.
2
3
3 of them.
455007 means 45500 multiplied by itself 7 times: 45500 x 45500 x 45500 x 45500 x 45500 x 45500 x 45500 = 4.037195464 x 1032
0.050200 mg has 5 significant figures. The zeros before the 5 are considered significant when they come after a decimal point.