Assigning Values in a Popup menu String

Hi, I am currently writing a simple code in which I want to choose a number from a drop-down string in two separate pop-up menus and then apply a function to these values where the answer is displayed in a textbox. For example, the user selects the number 4 from one drop-down and the number 9 from another. The user clicks the 'add' pushbutton and the number 13 is displayed in the answer textbox.

My issue is with converting the string values to text. I am currently using the code below:

popupmenu1 = get(handles.popupmenu1, 'Value');
input1 = str2num(get(handles.popupmenu1,'String'));

Answer 1

[Image Analyst]

Try something like this:

selectedItem1 = get(handles.popupmenu1, 'Value');
list1 = get(handles.popupmenu1, 'String');
input1 = str2double(list1{selectedItem1});
selectedItem2 = get(handles.popupmenu2, 'Value');
list2= get(handles.popupmenu2, 'String');
input2 = str2double(list2{selectedItem2});
results = input1 + input2;