Below is an context that describes a sql query, paired with an question that provides further information. Write an answer that appropriately completes the request.  # noqa: E501
### Context:
CREATE TABLE table_22078906_2 (no_in_series VARCHAR, us_viewers__millions_ VARCHAR)
### Question:
What number episode in the series was watched by 15.89 million U.S. viewers? 
### Answer:
SELECT no_in_series FROM table_22078906_2 WHERE us_viewers__millions_ = "15.89"