Private Function PercentChangeVerify()
    ' Test the PercentChange function.

    Debug.Assert PercentChange(100, 200) = 100
    Debug.Assert PercentChange(100, 150) = 50
    Debug.Assert PercentChange(100, 100) = 0
    Debug.Assert PercentChange(100, 50) = -50
    Debug.Assert PercentChange(100, 0) = -100

    Debug.Assert PercentChange(10, 100) = 900
    Debug.Assert PercentChange(10, 50) = 400
    Debug.Assert PercentChange(10, 20) = 100
    Debug.Assert PercentChange(10, 15) = 50
    Debug.Assert PercentChange(10, 10) = 0
    Debug.Assert PercentChange(10, 5) = -50
    Debug.Assert PercentChange(10, 0) = -100
    Debug.Assert PercentChange(10, -5) = -150
    Debug.Assert PercentChange(10, -10) = -200

    Debug.Assert IsNull(PercentChange(Null, 3))
    Debug.Assert IsNull(PercentChange("Joe", 3))
    Debug.Assert IsNull(PercentChange(3, Null))
    Debug.Assert IsNull(PercentChange(3, "Joe"))

End Function