In final circuit using the 4-bit adder subtractor is a circuit that adds or subtracts depending on a control signal Cin

When Cin = 0 using addition A+B+0

When Cin = 1 using subtraction A-B= A+B’+1

And using 3 (7-segment decoder) to display the decimal values for input A, input B, and output value

And using LED to display overflow and carry out