Binary Coded Decimal (BCD) numbers express each digit in a –

In the BCD system (specifically the common 8421 BCD), each decimal digit (0 through 9) is converted into its 4-bit binary equivalent.

• The "Nibble": In computing, a group of 4 bits is called a nibble.

• Representation: Since a nibble can represent 16 values (2^4), and decimal only requires 10 (0–9), BCD uses the first 10 combinations. The remaining 6 combinations (1010 through 1111) are considered invalid in standard BCD.

• Example: The decimal number 25 would be represented in BCD as:

  • 2 =0010 (one nibble)

  • 5 = 0101 (second nibble)

  • Result: 0010 0101