float(9**x) == 9**x = True , if x <= 16 but False if x> 16 why?

Question

converting int into float

Answer 1

That's because you're reaching maximum float precision. If you print the values when x=17, you'll understand what's happening.
Nice catch!

Answer 2

I used to think float just adds ".0" at the end of a int . But now I think it does something else. Can you please explain what it does actually?