A reason for granting quantity discount is to encourage bulk purchases. When a customer purchases a large quantity of a product, the seller may offer a discount on the total price of the goods. This discount is called a quantity discount, and it's intended to encourage the customer to buy more items at once. By offering quantity discounts, the seller can increase sales volume, reduce inventory costs, and create stronger relationships with customers who are buying in large quantities. Thus, the main purpose of a quantity discount is to incentivize customers to buy more products at once, which benefits both the buyer and the seller.