The book contains a large variety of basic aspects in elementary mathematics as well as a long list of original exercises and problems, some of these published in famous math magazines such as Crux Mathematicorum, The Pentagon Journal, La Gaceta de la RSME, Romanian Mathematical Magazine, Gazeta Matematică, Argument, Cardinal, Elipsa. It can well serve as a useful dictionary of problem-solving for teachers and students preparing for mathematical competitions. \n