The excess-3 binary code is an unweighted self-complementary BCD code. It is an important BCD code, is a 4-bit code and used with BCD numbers. Self-Complementary property means that the 1’s complement of an excess-3 number is the excess-3 code of the 9’s complement of the corresponding decimal number. The excess-3 code for 3(0011) is 0110 and to find the excess-3 code of the complement of 3, we just need to find the 1’s complement of 0110 -> 1001, which is also the excess-3 code for the 9’s complement of 3 -> (9-3) = 6.
Excess-3 Addition Algo:
1. Convert BCD numbers to Excess-3 codes
2. Add the excess-3 codes
3.
If a carry is there
Add 3 with the result
else
Subtract 3 from the result
Ans A)