We'll try to design a new kind of number. This is no easy task when Python already offers integers of indefinite precision, rational fractions, standard floats, and decimal numbers for currency calculations. We'll define a class of "scaled" numbers. These are numbers that include an integer value coupled with a scaling factor. We can use these for currency calculations. For many currencies of the world, we can use a scale of 100 and do all our calculations to the nearest cent.

The advantage of scaled arithmetic is that it can be done very simply by using low-level hardware instructions. We could rewrite this module to be a C-language module and exploit hardware speed operations. The disadvantage of inventing new scaled arithmetic is that the decimal package already does a very neat job of exact decimal arithmetic.

We'll call this FixedPoint class because it will implement a kind of fixed decimal point number. The scale factor will be a simple integer, usually a power...