Following are the values given above in 2's complement, using various bit sizes.

number     4 bits     8 bits     12 bits
------     ------     ------     -------
0          0000       00000000   000000000000
1          0001       00000001   000000000001
-1         1111       11111111   111111111111
-15        can't do   11110001   111111110001
7          0111       00000111   000000000111
-7         1001       11111001   111111111001
8          can't do   00001000   000000001000
576        can't do   can't do   001001000000
-576       can't do   can't do   110111000000