user: Question: What is the number of played when points against 645?
Columns: ['Position', 'Club', 'Played', 'Won', 'Drawn', 'Lost', 'Pts For', 'Pts Agst', 'B.P.', 'Points']
Types: ['real', 'text', 'real', 'real', 'real', 'real', 'real', 'real', 'real', 'real']
Sample row: [1.0, 'Castleford Tigers', 18.0, 17.0, 0.0, 1.0, 860.0, 247.0, 0.0, 51.0]
SQL:

assistant: SELECT "Played" FROM "Table" WHERE "Pts Agst" = 645.0;