Jez, why not implement or use a BCD library?

When I worked at Burroughs our mainframe was basically a 4 bit BCD machine, where data was represented by BCD, using as many digits as required. No precision lost due to binary rounding either (which is why they were used in banking, they didn't want to loose those fractional pennies!).

It should be fairly straight-forward to implement multiply and divide functions that could handle various length BCD operands, especially if the functions were recursive.

Just a thought.

Dennis