How many significant figures in 10200?

All zeros appearing in a number without a decimal point and to the right of the last nonzero digit are not significant unless indicated by a bar. Example: '1300' has two significant figures: 1 and 3. The zeros are not considered significant because they don't have a bar. However, 1300.0 has five significant figures.

So 10200 has 3 significant figures because it does not have a decimal point so the zeros after the 2 are not considered significant.