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_19236587_4 (series_no VARCHAR, uk_viewers__million_ VARCHAR)
### Question:
What's the series number of the episode seen by 2.43 million viewers in the UK?
### Answer:
SELECT series_no FROM table_19236587_4 WHERE uk_viewers__million_ = "2.43"