A question to get you started.
This is not the entire task, just a starting point. See where it takes you!
Write down all the characteristics of 231 that you can think of.
Create a problem from a subset of those characteristics.
Try to solve the problem.
Here are some ideas students have had while working on this problem.
You may find inspiration in their ideas!
This is a list of questions you can ask yourself or your students while working on this problem.
Naturally this isn't a complete list, but it will take you down one path.
This section will give you hints on some parts of the problem.
Expanding a section will reveal potential spoilers. If you only want a small hint, tread carefully.
What are you stuck on?
This section contains a "complete" path through this problem.
It covers only one path of many that could be taken, and there are still plenty of unanswered questions.
If you haven't tried the problem for yourself yet, and don't want it spoiled, don't read this section!