Patent ID: 7899854

Claim:
A computational device, comprising: a processor for performing mathematical computations, a user interface, comprising: a plurality of functional buttons each associated with one of a plurality of variables in a mathematical equation defining a relationship among said variables, wherein said mathematical equation comprises a loan equation characterized by any of a simple or compound interest, and a display, wherein in response to selection of any of said buttons by a user, said processor effects presentation of one or more prompts in said display to invite the user to enter values for variables associated with buttons other than that selected by the user, and wherein upon entry of the last variable value, said processor calculates a value for the variable selected by the user and presents said calculated value in the display, and wherein said device further comprises three additional buttons one of which is associated with entering a start date of the loan, another with entering an end date of the loan and the third with entering a date for which a pay-off amount of the loan is desired.