An add-in that extends Microsoft Excel 97 usage to applications dealing with uncertain data and involving problem solving under user-given constraints. Interval Solver allows the user to exploit uncertain numerical values represented asintervals in calculations. Function, equation, and inequality constraints can be used and solved. Just type in the equations as they are on the sheet, and Excel becomes a mathematician. Version 3.0 handles integer intervals, logic constraints, and adds additional arithmetical functions and a Model Converter to Excel's own Solver.