Calculating, the act of quantifying and manipulating numbers, is the foundation of human civilization. From simple tally marks to sophisticated computational tools, our ability to calculate has driven technological progress, scientific discovery, and economic growth. This book traces the evolution of calculating devices, from the abacus to modern computers. It explores the interconnected development of mathematical theory and practical application, highlighting key concepts like algebra, geometry, and calculus. Beyond mathematics, the book examines the profound impact of calculation on various aspects of modern life, from standardized testing to scientific research and medical innovation. It acknowledges the triumphs and limitations of widespread calculation in the 21st century, aiming to provide a comprehensive and accessible account of its evolution, encouraging readers to appreciate its power and inherent limitations.