The Single-Electron (SE) summing-inverter (SI) NOR and NAND gates are among the basic functional SE circuits. In this paper, the design of multi-input SE SI NOR and NAND gates are reviewed. Novel SE decimal-to-BCD encoders and binary decoders, which are composed of SI gates, are designed for all combinations of active inputs and outputs. The simulated designs work properly with only one voltage source of 500 mV for a wide range of temperatures (from 40K to 400K). The detailed schematic diagrams along with the corresponding SIMON 2 simulation results at room temperature (that include input and output signals as well as the stability diagrams) of the novel SE decimal-to-BCD encoders as well as the developed SE binary decoders are presented.