user: Question: What is the total number of Viewers when the rank is #40?
Columns: ['Episode #', 'Title', 'Air Date', 'Rating', 'Share', '18–49', 'Viewers', 'Rank']
Types: ['real', 'text', 'text', 'real', 'real', 'real', 'real', 'text']
Sample row: [42.0, '"The Manhattan Project"', 'September 25, 2008', 6.6, 11.0, 3.3, 9.77, '#26']
SQL:

assistant: SELECT SUM("Viewers") FROM "Table" WHERE "Rank" = '#40';