What is the number of the credit card that Frank-Paul Santangelo used to purchase root beers on 2014/7/7?
number of the credit card refers to CreditCardNumber; on 2014/7/7 refers to TransactionDate = '2014-07-07';
SELECT DISTINCT T2.CreditCardNumber FROM customers AS T1 INNER JOIN `transaction` AS T2 ON T1.CustomerID = T2.CustomerID WHERE T1.First = 'Frank-Paul' AND T1.Last = 'Santangelo' AND T2.TransactionDate = '2014-07-07'