A, B, C and D

$\begin{array}{ccccc}A& B & C & D \\ \times &&&9 \\ \hline D & C & B & A \\ \hline \end{array}$

Here $A = 1, B=0 , C = 8$ and $D = 9$

$\begin{array}{ccccc}1& 0 & 8 & 9 \\ \times &&&9 \\ \hline 9 & 8 & 0 & 1 \\ \hline \end{array}$

Hence $\overline{ABCD} = \boxed{1089}$