Not sure what you're talking about here, but maybe something like this ...
Public blnRan as boolean
Sub Testing()
Dim rngCalc as range
Set rngCalc = Workbooks("Book1.xls").Sheets("Sheet1").Range("A1").Value
If y = "met" Then
If blnRan = False Then
rngCalc = rngCalc.Value - x
blnRan = True
End If
End If
End Sub