What number episode in the series was watched by 15.89 million U.S. viewers?
CREATE TABLE table_22078906_2 (
    no_in_series VARCHAR,
    us_viewers__millions_ VARCHAR
)
SELECT no_in_series FROM table_22078906_2 WHERE us_viewers__millions_ = "15.89"
Below are sql tables schemas paired with instruction that describes a task. Using valid SQLite, write a response that appropriately completes the request for the provided tables. ### Instruction: What number episode in the series was watched by 15.89 million U.S. viewers? ### Input: CREATE TABLE table_22078906_2 (
    no_in_series VARCHAR,
    us_viewers__millions_ VARCHAR
) ### Response: SELECT no_in_series FROM table_22078906_2 WHERE us_viewers__millions_ = "15.89"