This book is written in such a way that each student starts from the theory and its basic applications, continues with solving exercises whose difficulty progressively increases, and gradually reaches the level of solving complex and combinatorial problems. Each chapter of the book contains:

• Basic theory and its applications.
• Solved exercises.
• Questions to answer, of all difficulty levels.
• Exemplary solutions to the questions from the Question Bank.
• Problems that require special mathematical thinking.
• Evaluation criteria.

At the end of the book, there are detailed solutions to the exercises from the school textbook.