All problems © Copyright 1999 Stan Wagon, Rob Leduc. Reproduced with permission.
- Problem 900: Friendly Sets
- Problem 899: Circles Need Four Colors
- Problem 898: An Almost-Regular Tetrahedron
- Problem 897: A GCD Problem
- Problem 896: A Special Graph
- Problem 895: Polar Visibility
- Problem 894: A Lattice Optimization Problem
- Problem 893: Morley's Ghost
- Problem 892: Banish the Magic
- Problem 891: A Funny Function
- Problem 890: Reconstruct the Dominoes
Please don't ask us for answers! Solutions for almost every problem are posted to the mailing list, but at Professor Wagon's request we do not reproduce them here. If you can't sleep without knowing the answer to one of these problems, please contact Professor Wagon at email@example.com.