1000 Math Gems Pdf [upd] -

Always respect copyright. Some "Math Gems" books (like those by Ross Honsberger or the Art of Problem Solving series) are under copyright. However, many educators have released public domain or Creative Commons compilations.

1000 Math Gems collects exactly such items. They are arranged not by difficulty but by theme: number theory, geometry, combinatorics, probability, analysis, and logic. You can open the book anywhere—page 47, gem #237—and within two minutes you’ll find something to smile at. 1000 math gems pdf

A mathematical gem has three qualities: