It is just about impossible to think of a mathematical puzzle that has not been previously dissected on the Internet. When I was in high school, the students often challenged each other in the morning before classes with mathematical puzzles: Prove which is greater, π^e or e^π were typical problems. For every problem I can remember from high school, I have found a solution on the internet.
I have submitted several puzzlers to the black hole of Car Talk which I took from eastern European tech school entrance exams. (The problems were stated in English, which required the student to be proficient in English as well as mathematics.) Those problems, as far as I can tell, have never appeared on the internet. However, I don’t think Car Talk takes puzzlers from readers anymore. Most of the puzzlers over the past few months can be found in the Car Talk Puzzles Archives.
In closing, I’ve a puzzler to chew on:
Given the equation aⁿ + bⁿ = cⁿ, a, b, c, n integer, show that the equation has no solution for n > 2.
That should keep some posters busy for awhile.