The operator for joining arguments in Excel is the comma.
If your values are coming through as text, use the VALUE() function to turn them back into digits. (What I tend to do in this situation is mark then end of the column next to the data range, and then create a formula at the top to do what I need. In this case, it would be =VALUE([CellReference]). Then I copy that formula down to the mark, copy the formula range and paste values over the source column.)