This example uses the FreeFile function to return the next available file number. Five files are opened for output within the loop, and some sample data is written to each.
Dim MyIndex, FileNumber
For MyIndex = 1 To 5 ' Loop 5 times.
FileNumber = FreeFile ' Get unused file
' number.
Open "TEST" & MyIndex For Output As #FileNumber ' Create file name.
Write #FileNumber, "This is a sample." ' Output text.
Close #FileNumber ' Close file.
Next MyIndex