A computer system, and methods for making and using it, for manipulating digital electrical signals to produce an illustration of a decomposition of property into separately valued components. The computer system includes a digital electrical computer controlled by a processor. There is a first logic means controlling the processor in manipulating digital electrical signals representing input data to the computer, the input data characterizing at least two components decomposed from the property, the manipulating including transforming the digital electrical signals into modified digital electrical signals representing respective values for each of the components, the values being computed to reflect taxation for the components. Input means is coupled to the computer and operable for converting the input data into the digital electrical signals and communicating the digital electrical signals to the computer. Output means is coupled to receive the modified digital electrical signals from the computer and to converting the modified digital electrical signals representing the respective values into an illustration of the computed respective prices. The property can be real estate or tax-exempt securities.