Sub VisibleArea()
     ActiveWindow.VisibleRange.Select
     Dim aCell As Range, mR As Range
     Set mR = Selection
     Dim x As Integer
     x = InputBox("Введи число от 0 до 9")
     Dim iInt As Integer
     For Each aCell In Selection.Cells
         aCell = CInt(1 + 99 * Rnd)
         aCell.NumberFormat = "@"
         aCell.Value = CStr(aCell.Value)
         If InStr(1, aCell, x) > 0 Then
             For i = 1 To Len(aCell.Value)
                 If Mid(aCell, i, 1) = x Then
                     aCell.Characters(i, 1).Font.ColorIndex = 3
                 Else
                     aCell.Characters(i, 1).Font.ColorIndex = xlAutomatic
                 End If
             Next
         End If
     Next
     Set mR = Nothing
End Sub

Sub test()
      With Sheets(3)
          .UsedRange.Clear
          .[a1:c20].NumberFormat = "@"
          For Each c In .[a1:c20].Cells
              c.Value = CStr(CInt(Rnd(1) * 1000))
          Next
          s = "5"
          For Each c In .[a1:c20].Cells
              For i = 1 To Len(c.Text)
                  If Mid(c.Text, i, 1) = s Then c.Characters(i, 1).Font.ColorIndex = 3
              Next
          Next
      End With
End Sub