If you normally use Purchase Orders to pay for your office supplies, you must set up a revolving credit account with us. Fill out an application here. Purchase Order numbers can be entered at the Payment Information screen when you place your order or on the Review Order page. You may also use a major credit card—MasterCard, American Express, VISA or Discover—to pay for your order. Please note that the Purchase Order number is for your records only. It will be referenced on your packing slip to make your record keeping easier.