These are puzzles that I have either invented or “acquired” over the years. I have avoided problems that have appeared many times in other puzzle books (You have 12 coins, one of which is either light or heavy...). The puzzles are presented here without solutions because, of course, the joy of a puzzle is in the solving, not in the answer. If you have questions about any of these, if you need a hint, or if you would like to share solutions or other insights, please send an email to deanbal (at) comcast (dot) net.

Here is a list of my puzzles that were selected for publishing in the Riddler column on fivethirtyeight.com. All of these puzzles have a link to their answers revealed in the following week's column.

Some of these puzzles have led to new sequences being published in the Online Encyclopedia of Integer Sequences. Here are links to those sequences: