Binary Coded Decimal Numbering System otherwise known as BCD Code is a process for converting decimal numbers into their binary equivalents. BCD code is more also known as 8421 BCD code.
The BCD equivalent of a decimal number is written by replacing each decimal digit in the integer and fractional parts with its four bit binary equivalent.
0 0000 1 0001 2 0010 3 0011 4 0100 5 0101 6 0110 7 0111 8 1000 9 1001
Electronics, true BCD code uses 0 to represent a switch that is ON and 1 for a switch that is off.