What do you mean by 8421 code?

The 8421 code, also known as binary-coded decimal (BCD), is a way of encoding decimal numbers in a binary format. In this code, each digit of a decimal number is represented by its equivalent four-bit binary value, where the weights of the bits are 8, 4, 2, and 1. For example, the decimal number 25 is represented in 8421 code as 0010 0101, corresponding to the digits 2 and 5. This coding system allows for easy conversion between decimal and binary, making it useful in digital systems and applications.