A textbook suitable for undergraduate courses. The materials are presented very explicitly so that students will find it very easy to read. A wide range of examples, about 500 combinatorial problems taken from various mathematical competitions and exercises are also included. Contents:Permutations and CombinationsBinomial Coefficients and Multinomial CoefficientsThe Pigeonhole Principle and Ramsey NumbersThe Principle of Inclusion and ExclusionGenerating FunctionsRecurrence Relations Readership: Undergraduates, graduates and mathematicians. keywords:Binomial Coefficients;Multinomial Coefficients;Euler ϕ-Function;Enumerative Combinatorics;Addition Principle;Multiplication Principle;Combination;Permutation;Identities;Pigeon Hole Principle;Ramsey Numbers;Principle of Inclusion and Exclusion;Stirling Numbers;Derangements;Problem of Ménages;Sieve of Eratosthenes;Generating Functions;Partitions of Integers;Exponential Generating Functions;Recurrence Relations;Characteristic Polynomial;Catalan Numbers “This book should be a must for all mathematicians who are involved in the training of Mathematical Olympiad teams, but it will also be a valuable source of problems for university courses.” Mathematical Reviews