The book describes the importance of arithmetic functions in modern digital VLSI system. Many research efforts have focused on designing faster and more efficient adder architectures and resulted in a larger number of adder architectures. Some examples of architectures are the Ripple carry adder which, generates carries in series, the carry look-ahead adder which attempts to speed-up the carry propagation by using additional logics, group generate and propagate, and the parallel prefix adder which extends from the idea of carry look-ahead computation. The parallel prefix adders are a more general form where a network is used to pre-calculate the carry signals.