Thanks for noticing! There is much simpler fix though (see my commits) :)

it seems that the variable naming used in the solution is not consistent with the explanation though.

Also, I observed that (x + y*n0)//z == math.floor(x + y * math.sqrt(n)) // z always seems to hold for the given initialization of x, y, and z. Why is this the case? (It's not true if we are allowed to initialize x, y, and z arbitrarily.)