This book is meant for computer scientists, researchers, practitioners, and students looking for a fast algorithm for performing arithmetic computations over big-integer numbers. As it provides complete pseudo-code, implementation, and source-code, this book is also a great reference for application developers to build big numbers-capable applications. In fact, four new algorithms are proposed in this book for handling arithmetic addition and subtraction of big-integer numbers whose length is much greater than 64 bits. The algorithms execution runtime is outstanding as they outperform other existing solutions by wide margins.