An $$N$$-bit carry look ahead adder, where $$N$$ is a multiple of $$4,$$ employs $${\rm I}cs$$ $$74181$$ ($$4$$bit $$ALU$$) and $$74182$$ ($$4$$ bit carry look ahead generator). The minimum addition time using the best architecture for this adder is

Both’s algorithm for integer multiplication gives worst performance when the multiplier pattern is