This 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 mathematical magazines such as American Mathematical Monthly, Crux Mathematicorum, The Pentagon Journal, SSMA Magazine, MathProblems Journal, La Gaceta de la RSME, Romanian Mathematical Magazine. The author has created the only Interactive Mathematical Journal in Romania (www.ssmrmh.ro) with 4 500 000 visitors in 18 months. The book is a small part of this Interactive Mathematical Journal.