Display Omitted Simplified logic and structure for 8421-5421 BCD multiplier are proposed.With a novel 4221 BCD full adder, 4221-8421 conversion is no longer needed.4221 BCD multiplier using the new 4221 BCD full adder is proposed.The proposed 8421-5421 multiplier gives the best performance ever. High-performance, area and power efficient hardware implementation of decimal multiplication is preferred to slow software simulations in various key scientific and financial applications, where errors caused by converting decimal numbers into their approximate binary representations are unacceptable. This paper presents a parallel architecture for fixed-point 8421-BCD-based decimal multiplication. In essence, it applies a hybrid 8421-5421 recoding scheme to generate partial products, and accumulates them with 8421 carry-lookahead adders organized as a tree structure. In addition, we propose a 4221-BCD-based decimal multiplier that is built upon a novel 4221-BCD full adder; operands of this 4221 multiplier are directly represented in the 4221 BCD. The proposed 16×16 decimal multipliers are compared with other best-known decimal multiplier designs with a TSMC 90-nm technology, and the evaluation results show that the proposed 8421-5421 multiplier achieves the lowest delay and area, as well as the highest power efficiency, among all the existing hardware-based BCD multipliers.