Some people dislike calculating restaurant tips. Hugh Loebner patented a method for restaurant patrons to not calculate a tip.
U.S. patent # 6019393, “Planar means for indicating a gratuity as a function”
Issue date: Feb 1, 2000
Inventor: Hugh Gene LoebnerOptional gratuities in the food and beverage industry may be defined on a planar surface as a percentage function of the cost of meals instead of an absolute dollar amount. This eliminates the necessity of the customer having to perform arithmetic calculations.
Inventor Loebner is a proud customer of many institutions.
(Thanks to Angie Boyter for bringing this to our attention.)

