I've look at your workbook. It's nothing like the image attached in your first post and there is still nothing to indicate what any input boxes might be used for.
Perhaps you want code like the following:
Code:
Sub CombineValues()
Dim i As Long
With ActiveSheet
For i = 1 To .Range("B" & .Cells.SpecialCells(xlCellTypeLastCell).Row).End(xlUp).Row
.Range("B" & i).Value = .Range("A" & i).Value + Evaluate(.Range("B" & i).Value)
.Range("B" & i).NumberFormat = "General"
Next
End With
End Sub