While carrying out the long division method, it always converts the given expression in the simplest form. That means as far as possible, it should be in form of Z divided by some polynomial. |Z| > 1 it is causal sequence. For the causal sequence the denominator polynomial should have maximum power of Z transform on its left. Thus the given expression is in the total proper form.
Find inverse Z transform of X(z) is = Z/Z-1 |Z|>1
X(Z) = 1 + Z-1 + Z-2 + Z-3+..........
∞
X(Z) = ∑ x(n) Z-n
n=0
X(Z) is = x(0) + x(1) Z-1 + x(2) Z-2 + x(3) Z-3
X(n) = {x(0) , x(1), x(2), x(3) }
x(n) = { 1, 1, 1, 1 }
x(n) = u(n)
Z-1{Z-1/Z-1} = u(n)
This is a standard Z transform pair.