Excel 2007 : Calling functions based on input values in Excel 07 (functions array?)

Try UDF. I created a custom function called XYZ with 2 inputs required. X is the value, y is the item #

Function XYZ(X As Double, Y As Integer) As Double
Select Case Y
    Case 1: XYZ = X - 6
    Case 2: XYZ = X + 91
    Case 3: XYZ = X / 2
    Case 4: XYZ = X * 21
    Case 5: XYZ = Sqr(X)
End Select
    
End Function