user: Question: How many episodes hve 4.50 million viewers?
Columns: ['Episode', 'Title', 'Directed by', 'Written by', 'UK viewers (million)', 'Share (%)', 'Original air date']
Types: ['real', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: [1.0, '"Episode 1"', 'Bharat Nalluri', 'Ben Richards', '4.50', '17.9', '7February2011']
SQL:

assistant: SELECT COUNT("Episode") FROM "Table" WHERE "UK viewers (million)" = '4.50';