Question

How many significant figures are in 0.0?

And how about 0.00?

Answer 1

0. Because 0 is not a significant figure. if you had said 12.00 or 56.77 you would have 2 for 12.00 the 1, and 2. Then for 56.77 you would have 4 - 5,5,7,7. Basically, any number is significant with the exception of the zero.