return int64MultiplyScale100(base)
	case 3:
		return int64MultiplyScale1000(base)
	case 6:
		return int64MultiplyScale(base, 1000000)
	case 9:
		return int64MultiplyScale(base, 1000000000)
	default:
		value := base
		var ok bool
		for i := Scale(0); i < scale; i++ {
			if value, ok = int64MultiplyScale(value, 10); !ok {
				return 0, false
			}
		}
		return value, true
	}
}

	for _, a := range []int64{0, -1, 1, 10, -10, mostPositive, mostNegative, -mostPositive} {
		for _, b := range []int64{1, 2, 10, 100, 1000, mostPositive} {
			expect, expectOk := int64Multiply(a, b)

			c, ok := int64MultiplyScale(a, b)
			if c != expect {
				t.Errorf("%d*%d: unexpected result: %d", a, b, c)
			}
			if ok != expectOk {
				t.Errorf("%d*%d: unexpected overflow: %t", a, b, ok)
			}
		}