Surajit Basu
This is a collection of puzzles requiring in most cases – high school math. The purpose is not necessarily to solve these problems, but to get you to think about different types of math puzzles. Many of the puzzles are introductions to different areas of math. Most of these puzzles can be done mentally. If you have to write, expect to write no more than a page. Pictures are useful.
Read this work at the World Public Library (library card needed).