First of all, a must be 1, otherwise five digits will appear after multiplying by 9.

Then d must be equal to 9,9 * 9 = 81,

B should not be carried forward, so the choice of B is 0 or 1. If 1 is selected, there is C*9+8= 1, because if B= 1, C*9 cannot be carried forward, and 9C+8= 1 is invalid, that is to say, B=

The answer is A= 1 B=0 C=8 D=9.