If the problem is remembering wether to add or subtract 1 after complementing, then one just needs to take decimal 0 = 0x00 as example: complement (0xFF) then n

If the problem is remembering wether to add or subtract 1 after complementing, then one just needs to take decimal 0 = 0x00 as example: complement (0xFF) then necessarily add 1 (0x00) to get -0 = 0.