Abstract: A combinational weighing system with a plurality of weighing devices employs at least three central processing units such as microprocessors. One keeps monitoring the weight information from the weighing devices and analyzes stability of weight data. Another one controls the charging and discharging of the weighing devices. The third performs combinational computation to select a combination. The system has increased flexibility regarding operation and adjustments, and allows efficient methods of zero-point and span adjustment of weighing devices. Its compact unitized input-output unit allows the user to operate the system interactively.