binary coded decimal

from The Free On-line Dictionary of Computing (8 July 2008)

binary coded decimal
BCD
packed decimal

   <data> (BCD, packed decimal) A number representation where a
   number is expressed as a sequence of decimal digits and then
   each decimal digit is encoded as a four-bit binary number (a
   {nibble}).  E.g. decimal 92 would be encoded as the eight-bit
   sequence 1001 0010.

   In some cases, the right-most nibble contains the sign
   (positive or negative).

   It is easier to convert decimal numbers to and from BCD than
   binary and, though BCD is often converted to binary for
   arithmetic processing, it is possible to build {hardware} that
   operates directly on BCD.

   [Do calculators use BCD?]

   (2001-01-27)