In Number Theory, Logic, and Cryptography


This site is not about the great unsolved problems in mathematics. For those, see the extensive list at http://mathworld.wolfram.com/. For the seven Millennium problems, each of which has a prize value of one million dollars, see http://www.claymath.org/millennium-problems.


This site concentrates only on problems in number theory, logic, and cryptography that are easily understandable to the amateur. To be eligible for listing, the problem must be explainable on a single screen (perhaps 200 words), using simple terminology.

That is not to say that any of the problems here are trivial - very far from it. They are all unsolved, despite often many years of attention from very highly trained, very intelligent people. So, all of the problems here are hard. Very hard.

This site also provides an opportunity for authors to have their contributions published. If you think you have a valuable contribution to any of these problems, please read the FAQ before asking for it to be published on the Solutions page. The FAQ will strongly suggest that you publish in a recognized journal, and use this site only as a last resort if, after reading the referees' reports, you are still convinced you have the solution (or a significant part thereof).

There is a companion group, https://groups.io/g/UnsolvedProblems/topics, where these problems and others can be discussed.


The developer of this site is offering prizes for many of the problems on this site. Please see the Prizes page for further details.



This web site developed and maintained by

Tim S Roberts

Email: timro21@gmail.com