MAMEWorld Forums - Programming - Binary-coded decimal arithmetic?

I have been looking for good algorithms for binary-coded decimal arithmetic. The best I have been able to find is
this page and it really doesn't go into as much detail as I would like. In particular, it says nothing about multiplication or division. Also, I suspect the addition and subtraction algorithms could be improved upon.

I want to know what algorithms for BCD arithmetic anyone might have come across in games. For example, I have seen Web pages giving very detailed information about the workings of Pac-Man, but of course they wouldn't have the "boring" stuff such as how the points are actually added up. Also, I am curious as to how games that multiply numbers (for example, Giga Wing, and some gambling games) do so.