n recent years, digital multiplication circuits are used extensively in microprocessors, signal processing, encoding algorithms as well as computing the efficacy of algorithms. 4 to 2 compressors are generally used for plus operations. The purpose of this study is to investigate these compressors and conducted researches in relation to the way of working and structures of 4 to 2 compressors. The methodology of this study is descriptive-analytical and data was gathered using different studies inside the country and out of country. Data collection instrument include articles, internet sources and written documents in this field that are collected by using fishing technique. The results of this study indicate that the main characteristics of 4 to 2 compressors are compression level of 2 and using as the base cell to male bigger compressors including 6 to 2, 9 to 2 and finally IEEE 754standard (compressor 27-2). But it seems that the result of researches conducted by engineers show that 4 -2 compressor is not able to multiply and plus of consecutive numbers. In Keyvan, a new technique is presented to plus numbers in which a circuit is designed by using multi-circuit logic that at the same time has all characteristics. In new design, in addition to simplicity of plus numbers, the delay for the best and worst path is exactly the same.