design a decimal adder for digits represented in the excess-3 code. Show that the correction after adding two digits with a 4-bit binary adder is as follows:
(a) The output carry is equal to the carry from the binary adder
(b) If the output carry = 1, then add 0011.
(c) If the output carry = 0, then add 1101.
(d) Construct the decimal adder with two 4-bit adders and an inverter.