What must you do in the Solver dialog to ensure variable cells are whole numbers?

To ensure that variable cells are whole numbers in the Solver dialog, selecting the "int" option in the operator drop-down is the correct approach. This selection is specifically designed to apply an integer constraint, which restricts the values of the designated variable cells to whole numbers only. This operation is crucial when you want to model scenarios where fractional values would not make sense, such as in inventory management or scheduling problems.

While typing a whole number into the Cell Reference input might seem relevant, it does not apply a constraint to the variable but rather sets a specific value, which would not allow Solver to optimize as intended. Adding a new variable constraint might seem like a viable option, but without specifically choosing the integer constraint, you won’t achieve the requirement of whole number values. Expanding the dialog for more options does not directly address the need to set the variables as integers; it merely provides additional features and settings, which may not be necessary for this specific requirement.

Therefore, choosing the integer option in the operator drop-down ensures that the variable cells are strictly limited to whole number values throughout the optimization process, maintaining the integrity of your model.