user: Question: What is the series number that has a production code of 50021–50025?
Columns: ['Number in series', 'Number in season', 'Title', 'Directed by', 'Original air date', 'Production code']
Types: ['real', 'real', 'text', 'text', 'text', 'text']
Sample row: [26.0, 1.0, '"The Case of the Mystery Weekend"', 'Bill Schreiner', 'September 21–25, 1992', '50021–50025']
SQL:

assistant: SELECT "Number in series" FROM "Table" WHERE "Production code" = '50021–50025';