Concatenate Argument into Excel Range

I have this Code, Where I need to do a Autofill in a Range, So the max Range is dinamic, so, i join this max Range with an argument, but this argument join like a String, and I need concatenate this argument with the letter Q, Like this. Argument = "168" this is the line code where i will do the autofill, So, facturasExcel.Selection.AutoFill facturasExcel.Range("Q2:Q+Argument"), xlFillDefault