Self complementing Codes

Question

This statement was deemed true: Given any self-complementing decimal code scheme, if we know the codes for the number 283, then we can deduce the codes for 671.

I wanna know why. I took Excess-3 BCD as the self complementing code:

0-0011
1-0100
2-0101
3-0110
4-0111
5-1000
6-1001
7-1010
8-1011
9-1100

So 283 = 0101 1011 0110 .

671 = 1001 1010 0011
So why is the statement as it is as 283-ex3 is not a 1s complement of 671-ex3?

Answer 1

Since it is self-complementing decimal code scheme, then the code for 9's compliment of 283 can be obtained by taking 1's complement of code for 283.

9's complement of 283 = 716

283 = 0101 1011 0110. so its 1's complement = 1010 0100 1001 will be the code for 716.

From this: code for 7 =1010, that for 1 =0100 and for 6 = 1001

So code for 671 = 1001 1010 0100