A combined adder for N logical bits to produce a sum from a first addend having N first addend bits and a second addend having N second addend bits. A least significant adder produces a segment sum of the least significant bits and a carry out. Segment adder pairs are used for each higher order of significant sums. One segment adder produces a segment sum portion, and the other produces an incremented segment sum portion. Carry logic associated with each segment is utilized with a multiplexer to select the incremented segment sum portion or the segment sum portion. The selected segment sum portions are assembled with a most significant carry out to produce the sum.