user: Question: What is the length for iin range 51-55?
Columns: ['Issuing network', 'IIN ranges', 'Active', 'Length', 'Validation']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['American Express', '34, 37 [ dead link ]', 'Yes', '15', 'Luhn algorithm']
SQL:

assistant: SELECT "Length" FROM "Table" WHERE "IIN ranges" = '51-55';