What is patentable is "this circuit to compute the average" where the circuit is an adder that drops the bottom bit from the addends, instead ANDing the two bottom bits and using the result as a carry-in.
Though actually it shouldn't be patented because it's an obvious implementation of a math formula (and math is not patentable).
Though actually it shouldn't be patented because it's an obvious implementation of a math formula (and math is not patentable).