German pupils learn the ökonomisches Prinzip, the economic principle. It says that the ratio of effort to result should be as favorable as possible. It has two forms. The Maximalprinzip gets the most out of given means. The Minimalprinzip reaches a given goal with the least means, and it is also called the Sparprinzip, the saving principle.
School material from the publisher Klett explains it with a purchase. A man compares several offers for a laser printer.