Why do computer scientists and software developers actually need to study mathematics? How can mathematics assist them in programming? This textbook introduces first-year students to the language and methods of mathematics as a foundation for structured problem-solving, which is essential for developing software systems. Therefore, the didactic focus here is on demonstrating how mathematical concepts build on one another, what patterns emerge from them, and what clearly structured rules exist in mathematical reasoning (proofs). This book focuses on logic, set theory, discrete structures, and probability theory, aligning with the recommendations of ACM and IEEE for mathematics education in software engineering programs. Just like software development, mathematics cannot be learned solely through lectures.