Convert 5.764764764 ... to a rational expression in the form of a/b where b=0

Say x=5.764---

Then 1000x=5764.764---

Then 1000x-x = 5759

So 999x = 5759

So x=5759/999

I don't see how b can be 0 in this case ... what does that mean? You would never divide by 0 and live to tell about it, right?