To model this problem with the Mathematical Programming Add-in, select Nonlinear from the OR_MS menu. The Nonlinear Model Dialog presents the same options as the Linear Model Dialog except that it also asks for the number of extra columns. Although not necessary for this problem, we enter 1 as the number of extra columns to illustrate the effect. The remainder of the options on this dialog should be clear from the discussion of the Linear Model Dialog. There are no solver options because only the Excel Solver can handle nonlinear models. Although the Excel Solver does solve problems with integer variables, great care must be exercised when interpretting these answers. It is often true, that the Solver will deliver non-optimal results for integer-nonlinear problems.