Computing is revolutionizing the creative process, transforming how designers approach ideation, prototyping, fabrication, communication, and representation. Yet many lack the foundational knowledge needed to fully harness its potential. Designing with Algorithms: A Mathematical Guide bridges this gap, offering a comprehensive, step-by-step exploration of algorithmic practices applicable across diverse design fields. This guide begins with foundational theories, illuminating the role of mathematics and computational logic in design thinking. It progresses to practical techniques for creating parametric 2D and 3D geometries, grid systems, patterns, forms, and fonts. The book culminates in real-world case designs, showcasing diverse applications of generative algorithms across urban design, architecture, graphic design, typography, fashion, and more. Unlike software-specific guides, this book emphasizes process and adaptability, teaching readers to think algorithmically and develop skills transferable to any programming platform. Whether you’re a student, practitioner, or enthusiast, this book empowers you to future-proof your design practice and unlock the creative potential of computation.