But I will continue as planned: 8642. 
8642 has no bulls and one cow.
| # | guess | Bulls | Cows |
|---|---|---|---|
| 1 | 9753 | 2 | 1 |
| 2 | 8642 | 0 | 1 |
“And thus, 0 and 1 can be already eliminated.”
“Amazing, Holmes.”
“Elementary, my dear Watson, elementary.”
My next guess is 9653.
9653 yields two bulls and no cows.
| # | guess | Bulls | Cows |
|---|---|---|---|
| 1 | 9753 | 2 | 1 |
| 2 | 8642 | 0 | 1 |
| 3 | 9653 | 2 | 0 |
A clean shot: 6 will join 0 and 1, and 7 can’t wait to be promoted to the rank of bull.
Let’s try the following: 7853.
7853 has one bull and one cow.
| # | guess | Bulls | Cows |
|---|---|---|---|
| 1 | 9753 | 2 | 1 |
| 2 | 8642 | 0 | 1 |
| 3 | 9653 | 2 | 0 |
| 4 | 7853 | 1 | 1 |
My next guess is 9257.
Well, that didn’t take too long. Congratulations, PlaceboTarget, you have solved the puzzle.
| # | guess | Bulls | Cows |
|---|---|---|---|
| 1 | 9753 | 2 | 1 |
| 2 | 8642 | 0 | 1 |
| 3 | 9653 | 2 | 0 |
| 4 | 7853 | 1 | 1 |
| 5 | 9257 | 4 | 0 |
Thank you. 
When the stars align, everybody can get as sharp as a tack.

I will hold the trophy until someone guesses the next secret number:

Please submit your guesses and I’ll process them as soon as I find the time.

I have time for one guess before going to bed. How about 9876?
Thank you for your guess. 
| guess # | player | guess | bulls | cows |
| 1 | bibliophage | 9876 | 0 | 1 |
| guess # | player | guess | bulls | cows |
| 1 | bibliophage | 9876 | 0 | 1 |
| 2 | Aspidistra | 7654 | 0 | 2 |
| guess # | player | guess | bulls | cows |
| 1 | bibliophage | 9876 | 0 | 1 |
| 2 | Aspidistra | 7654 | 0 | 2 |
| 3 | Prof.Pepperwinkle | 3657 | 0 | 1 |
0152?
| guess # | player | guess | bulls | cows |
| 1 | bibliophage | 9876 | 0 | 1 |
| 2 | Aspidistra | 7654 | 0 | 2 |
| 3 | Prof.Pepperwinkle | 3657 | 0 | 1 |
| 4 | Prof.Pepperwinkle | 0152 | 0 | 2 |
| guess # | player | guess | bulls | cows |
| 1 | bibliophage | 9876 | 0 | 1 |
| 2 | Aspidistra | 7654 | 0 | 2 |
| 3 | Prof.Pepperwinkle | 3657 | 0 | 1 |
| 4 | Prof.Pepperwinkle | 0152 | 0 | 2 |
| 5 | Aspidistra | 4591 | 0 | 1 |