Abstract: A parallel combinational logic system has a shortened carry run for two binarily-coded numbers upon consideration of an input carry. In order to shorten the carry throughput time, two alternative carries are respectively formed, group-wise, from the sums of the operands in first combinational logic units, the actual result carries being selected therefrom and from a decision logic unit, upon consideration of other group carries. These result carries are supplied to second combinational logic units at whose inputs the operands to be combined are applied. Under the control of the result carries, the operands are combined group-wise with one another or, respectively, the final result is selected from two alternative intermediate results.