"Problem-Solving Through Problems" by Loren C Larsen (1983) was my favorite at high school. The sections headings of Chapter 1 on Heuristics give a flavor of i

"Problem-Solving Through Problems" by Loren C Larsen (1983) was my favorite at high school. The sections headings of Chapter 1 on Heuristics give a flavor of its approach: Search for a pattern; Draw a figure; Formulate an equivalent problem; Modify the problem; Choose effective notation; Exploit symmetry; Divide into cases; Work backward; Argue by contradiction; Pursue parity; Consider extreme cases; Generalize. Links: * Official Springer book web site: https://www.springer.com/gp/book/9780387961712 https://www.springer.com/gp/book/9780387961712 * Amazon: https://www.amazon.com/Problem-Solving-Through-Problems-Problem-Mathematics/dp/0387961712 https://www.amazon.com/Problem-Solving-Through-Problems-Prob... * Poor quality scanned PDF: https://math.la.asu.edu/~ifulman/spring13/mat194/problem-solving.pdf https://math.la.asu.edu/~ifulman/spring13/mat194/problem-sol...