The editors of the New Mathematical Library, in wishing to encourage significant problem-solving at the high school level, have published the following problem collections so far: NML 5 and 17 containing all annual contest problems proposed by the Mathematical Association of America through 1965; and NML 11 and 12 containing translations of all Eötvös Competition problems through 1928 and their solutions. The present volume is a sequel to NML 17 published at the request of the many readers who enjoyed the previous MAA problem books.

The MAA contests now contain 35 problems based entirely on the standard high school curriculum. To expedite grading of the approximately 400,000 papers written, each question is worded so that exactly one of five choices offered serves as a correct answer.

Each Eötvös contest, on the other hand, contains only three problems, based on the Hungarian high school curriculum, and often requiring ingenuity and rather deep investigations for their solution.

The MAA is concerned primarily with mathematics on the under-graduate level. It is one of three major mathematical organizations in America (the other two being the American Mathematical Society, chiefly concerned with mathematical research, and the National Council of Teachers of Mathematics, concerned with the content and pedagogy of elementary and secondary mathematics). The MAA also conducts the annual Putnam Competition for undergraduate students. Its journal, The American Mathematical Monthly, is famous for its elementary and advanced problem sections.