The function adds all the pairwise products of two lists, list1 and list2, and returns the result. The size of each list is n. How many times is the multiplication operation performed? Provide a reason to back up your answer.

def calculate(list1, list2): result = for i in range(len(list1)): for j in range(len(list2)): result += list1 [i] list2 [j] return result