![4 bit adder subtractor circuit](https://eevibes.com/wp-content/uploads/2022/06/4-bit-adder-subtractor-circuit.png)
The full adder is an added that takes three inputs &generates two outputs as a result. The first 2 inputs typically A & B, with the third being a C-IN input carry. Output carry generally labelled as C-OUT, whereas normal output labelled as S, that stands for SUM.