There is book1 where in one column are the names of old books , and in another the names of new ones (old ones need to be renamed in new ones). n,m-numbers. 

An error occurs: 

> 
> Run-time error ‘13’ Type mismatch in line 
> 
> 
> 

```
OldName = "" + n + ".xlsm"

```

Code:

```
    Sub Кл()

    Dim OldName, NewName
    Dim book1 As Workbook
    Dim t As Long, m As Long, n As Long

    Application.ScreenUpdating = False
    Application.Calculation = xlCalculationManual
    Application.EnableEvents = False

     Set book1 = Workbooks.Open("E:\Super M\Проект ставки\Поиск решения\Усов 
           7\вспомогательные программы\Книга в лист\виз.xlsx")
     For t = 3 To 5

      n = book1.Worksheets("общ").Range("C" & t).Value
      m = book1.Worksheets("общ").Range("C" & t).Offset(0, 1).Value

      OldName = "" + n + ".xlsm"
      NewName = "" + m + ".xlsm"

      Name OldName As NewName

      OldName = "E:\Super M\Проект ставки\Поиск решения\Усов 
            7\вспомогательные программы\Книга в лист\Отборные 
            условия\Откуда\" + n + ".xlsm"
      NewName = "E:\Super M\Проект ставки\Поиск решения\Усов 
              7\вспомогательные программы\Книга в лист\Отборные 
             условия\Куда\" + m + ".xlsm"

      Name OldName As NewName

      Next t
      book1.Close

      Application.ScreenUpdating = True
      Application.Calculation = xlCalculationAutomatic
      Application.EnableEvents = True

      End Sub

```