Doug C. answered • 03/21/19

Math Tutor with Reputation to make difficult concepts understandable

So, the digits can be represented by(assuming that A is the "first" digit.:

**A**.**2A**.**D-1**.**D**.**2A-1**.**2A-3**

The sum of those digits is 23, so 7A-5+2D = 23, or 7A+2D=28. The key is that A and D must be whole numbers between 0 and 9, so try some values for A and see if you can get D to be a whole number. For example if A = 1, then 2D = 21, D=10.5.so rule out A=1. Try A = 2. D=7, seems to work! Go from there.