The Green Book of Mathematical Problems (Dover Books on Mathematics)

This convenient volume offers a popular selection of 100 practice problems — with hints and solutions — for students preparing for undergraduate-level math competitions. The challenging brainteasers will also appeal to anyone interested in problems concerning real numbers, differential equations, integrals, polynomials, sets, and other mathematical topics.
The hints are very helpful and the solutions are easy to follow. Questions drawn from geometry, group theory and linear algebra involve subjects ranging from multivariate integration to finite series to infinite sums and classical analysis. The only prerequisite is a high school-level background in mathematics. Problem-solvers at varying degrees of proficiency will find this treasury of top-notch numerical puzzles an invitation to hone their mathematical skills as well as a source of stimulating entertainment.