Q7,p2,d14. The Excess-3 decimal code is a self-complementing code because

(A) The binary sum of a code and its 9’s complement is equal to 9.

(B) It is a weighted code.

(C) Complement can be generated by inverting each bit pattern.

(D) The binary sum of a code and its 10’s complement is equal to 9.

Answer A,C

Explanation.

Excess 3 code is generated by adding 3 and representing in binary form.

0 is represented     011.

1 isrepresented as 100

2  is represented as 101.

3 is represented as 110.

Let take case A.  1 is represented as (100)

9^th complement of (100) is 5 represenetd as (101) its sum is 0100+101=1001.equals to decimal 9.

In another case lets take the code 110.its 9’s complement is 3.

Addition 110+011=1001. Hence option A is true.

It is not weighted sum.

Self complimenting code produce 9’s complement on inverting bit.