a.scale = 0
		return true
	case a.scale == 0:
		c, ok := int64Multiply(a.value, b)
		if !ok {
			return false
		}
		a.value = c
	case a.scale > 0:
		c, ok := int64Multiply(a.value, b)
		if !ok {
			return false
		}
		if _, ok = positiveScaleInt64(c, a.scale); !ok {
			return false
		}
		a.value = c
	default:
		c, ok := int64Multiply(a.value, b)
		if !ok {
			return false
		}

		if scale >= int32(Nano) {
			shifted := num + denom

			var value int64
			value, err := strconv.ParseInt(shifted, 10, 64)
			if err != nil {
				return Quantity{}, ErrNumeric
			}
			if result, ok := int64Multiply(value, int64(mantissa)); ok {
				if !positive {
					result = -result
				}
				// if the number is in canonical form, reuse the string
				switch format {
				case BinarySI: