BCD code is a 4-digit Binary number code to represent a decimalism Number. 8421 yards are usually used (there are others for example 2421 yards and the remaining 3 yards).

Let's use 8421 code to explain.

four digit binary. They correspond to Number 8, 4, 2, and 1.

Example: 1010 then corresponds to the Number 8, 0, 2, 1 plus eleven

Example: 0101 then corresponds to the Number 0, 4, 0, 1 plus 5

2421 code is corresponding to 2, 4, 2, 1 four Number

Is it 8421 for the remaining 3 yards, but it should be reduced after 3.