human
Considering the provided database schema and associated query, produce SQL code to retrieve the answer to the query. 
###Database Schema: No. in series, No. in season, Title, Directed by, Written by, Original air date, Production code, U.S. viewers (millions)
###Question: Name the number in the series for when the viewers is 7.78
gpt
SELECT No. in series FROM table WHERE U.S. viewers (millions) = 7.78