About Combo Box
With a combo box, you can create a selectable list of items to calculate. When you select an item, Mathcad uses the corresponding value for calculating all the dependent regions. For items with multiple values, Mathcad returns a column vector. When you change your item selection, the calculations update to reflect the new item values. Combo box selection settings are saved between Mathcad sessions.
Adding a Combo Box
Click Input/Output > Combo Box.
If you are editing an equation , the combo box is added in the current position, else, the combo box is created in a new equation.
If you are editing a text region, a math region is inserted for the combo box.
* 
The combo box is disabled and cannot be added if there is a scoping in the equation.
The above rules apply to equation that are part of other controls (plots, specification tables, etc).
Was this helpful?