What are your favourite problems that you enjoy solving

1. Sudoku

2. Poker puzzles

3. Backgammon puzzles

4. Medical diagnoses

5. Predicting wildlife behavior

How do I get that lunker trout under the log to bite? How do I predict which 4sq. inches that raccoon will step on so I can safely trap and remove him from the chicken house? Etc

6. Dice problems