Mathematical puzzles online - Links to books and blogs

1. Sample puzzles of Martin Gardner, with solutions - The Guardian
2. Martin Gardner's best math puzzles - part 1 (The Math Dude)
3. Math questions (solvable online) for class 10 from NSTE
4. International Mathematical Olympiad - Question paper archive
5. Problem Solving Strategies - Arthur Engel - archive.org
6. Entertaining Math Puzzles, by Martin Gardner
7. Math Proof Training and Practice Forum
   
   Source https://www.physicsforums.com/forums/math-proof-training-and-practice.296
   Math Proof Training and Practice Forum at PhysicsForums.com