Private Function MantissaVerify()
    ' Test the Mantissa function.

    Debug.Assert Mantissa(1234) = 1.234
    Debug.Assert Mantissa(123.4) = 1.234
    Debug.Assert Mantissa(12.34) = 1.234
    Debug.Assert Mantissa(1.234) = 1.234
    Debug.Assert Mantissa(0) = 0
    Debug.Assert Mantissa(-1.234) = 1.234
    Debug.Assert Mantissa(-12.34) = 1.234
    Debug.Assert Mantissa(-123.4) = 1.234
    Debug.Assert Mantissa(-1234) = 1.234

    Debug.Assert Mantissa(1234001) = 1.234001
    Debug.Assert Mantissa(1234000) = 1.234

    Debug.Assert Approx(Mantissa(1.234E+37), 1.234)
    Debug.Assert Mantissa(1.234E-37) = 1.234
    Debug.Assert Mantissa(-1.234E-37) = 1.234
    Debug.Assert Approx(Mantissa(-1.234E+37), 1.234)

    Debug.Assert IsNull(Mantissa(Null))
    Debug.Assert IsNull(Mantissa("Joe"))

End Function