Although the speed advantage of using signed – digit number systems seemed to have been reduced significantly by reverse conversion owing to the carry – propagation, in this paper, it was shown that if typical reverse conversion algorithms were employed for signed – digit number systems, then no further carry propagation needed to transform the output from radix – complement form to other conventional forms. As a result the instantaneous delay caused by the reverse conversion of signed – digit number systems might be compensated by speed gain at later stages.