user: Question: What's the number of the episode seen by 2.24 million people in the US?
Columns: ['No.', '#', 'Title', 'Directed by', 'Written by', 'U.S. air date', 'Production code', 'U.S. viewers (million)']
Types: ['real', 'real', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: [175.0, 1.0, '"Savior"', 'Kevin G. Fair', 'Kelly Souders & Brian Peterson', 'September25,2009', '3X5251', '2.58']
SQL:

assistant: SELECT "#" FROM "Table" WHERE "U.S. viewers (million)" = '2.24';