A collection of puzzles ranging over geometry, probability,
number theory, algebra, calculus, and logic. Hints are provided, along with
answers, fully worked solutions, and links to related mathematical topics.
Many of the puzzles are elementary in their statement, yet challenging. New
puzzles are added on a regular basis.
A key feature of the site is the detailed exposition, from
first principles, of the puzzle solutions. Some of the puzzles are used to
showcase particular mathematical concepts. See, for example, puzzle 56, which
introduces a partition identity, and puzzle 63, where Ptolemy's Theorem
permits a surprisingly simple solution. Further references are provided with
many of the solutions.