def METHOD_NAME(self):
    v1, u1 = self.Q_(8.0, 's'), self.Q_(.7, 's')
    v2, u2 = self.Q_(5.0, 's'), self.Q_(.6, 's')
    v2, u3 = self.Q_(-5.0, 's'), self.Q_(.6, 's')
    m1 = v1.plus_minus(u1)
    m2 = v2.plus_minus(u2)
    m3 = v2.plus_minus(u3)
    for factor, m in zip((3, -3, 3, -3), (m1, m3, m1, m3)):
        r = factor * m
        self.assertAlmostEqual(r.value.magnitude, factor * m.value.magnitude)
        self.assertAlmostEqual(r.error.magnitude, abs(factor * m.error.magnitude))
        self.assertEqual(r.value.units, m.value.units)
    for ml, mr in zip((m1, m1, m1, m3), (m1, m2, m3, m3)):
        r = ml + mr
        self.assertAlmostEqual(r.value.magnitude, ml.value.magnitude + mr.value.magnitude)
        self.assertAlmostEqual(r.error.magnitude,
                               ml.error.magnitude + mr.error.magnitude if ml is mr else
                               (ml.error.magnitude ** 2 + mr.error.magnitude ** 2) ** .5)
        self.assertEqual(r.value.units, ml.value.units)
    for ml, mr in zip((m1, m1, m1, m3), (m1, m2, m3, m3)):
        r = ml - mr
        self.assertAlmostEqual(r.value.magnitude, ml.value.magnitude - mr.value.magnitude)
        self.assertAlmostEqual(r.error.magnitude,
                               0 if ml is mr else
                               (ml.error.magnitude ** 2 + mr.error.magnitude ** 2) ** .5)
        self.assertEqual(r.value.units, ml.value.units)