Moving on, this simple billing system project in Python focuses mainly on dealing with customer’s billing with their purchase quantity, and discount. At first, the system allows inserting the customer’s name, then the user can simply enter the item’s name and quantity he/she wants. After selecting all the product items, the system calculates the total payable bill with the expected discount percentage. At last, the system automatically creates an invoice receipt in a .txt format which includes the name of the customer, date, time of purchase, product item with quantity, unit price, and a total of each, discountable amount, and payable amount. All these sold product’s quantity is also deducted from the system which is system maintains it under products.txt file.