The goal: "Create an application which manages an inventory of products. Create a product class which has a price, id, and quantity on hand. Then create an inventory class which keeps track of various products and can sum up the inventory value." I figured out how to get a list of dictionaries, and then add up the price. My output isn't pretty, but before I continue, I would simply like general critique. class Product: def __init__(self, i, p, q): self.identification = i self.price = p self.quantity = q self.item_dictionary = {'ID: ': self.identification, 'Price: ': self.price, 'Quantity: ': self.quantity} class Inventory: def __init__(self): self.identification, self.price_list, self.quantity_list = [], [], [] self.products = [ product_1.item_dictionary, product_2.item_dictionary ] # Make list of item dictionaries for i in self.products: self.identification.append(i['ID: ']) self.price_list.append(i['Price: ']) self.quantity_list.append(i['Quantity: ']) # Make unique lists of ID, Price, and Quantity print(sum(self.price_list)) product_1 = Product(32, 23, 2) product_2 = Product(23, 65, 3) inventory_1 = Inventory()