Editing Excess-3 (section)

==Advantage==
The primary advantage of excess-3 coding over non-biased coding is that a decimal number can be [[nines' complement]]ed<ref name="Steinbuch_1962"/> (for subtraction) as easily as a binary number can be [[ones' complement]]ed: just by inverting all bits.<ref name="Steinbuch_1962"/> Also, when the sum of two excess-3 digits is greater than 9, the carry bit of a 4-bit adder will be set high. This works because, after adding two digits, an "excess" value of 6 results in the sum. Because a 4-bit integer can only hold values 0 to 15, an excess of 6 means that any sum over 9 will overflow (produce a carry-out).

Another advantage is that the codes 0000 and 1111 are not used for any digit. A fault in a memory or basic transmission line may result in these codes. It is also more difficult to write the zero pattern to magnetic media.<ref name="Steinbuch_1962"/><ref name="Bashe_1956"/><ref name="Mietke_2017"/>