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_15472061_1 (no_in_series VARCHAR, us_viewers__millions_ VARCHAR)
### Question:
Name the number in the series for when the viewers is 7.78
### Answer:
SELECT no_in_series FROM table_15472061_1 WHERE us_viewers__millions_ = "7.78"