q := Quantity{Format: DecimalSI}
		var order []int64
		for i := 0; i < 100; i++ {
			j := rand.Int63()
			order = append(order, j)
			q.Add(*NewScaledQuantity(j, Scale(k)))
		}
		for _, j := range order {
			q.Sub(*NewScaledQuantity(j, Scale(k)))
		}
		if !q.IsZero() {
			t.Errorf("addition and subtraction did not cancel: %s", &q)
		}
	}
}