<p>The arithmetic element determines an exchangeable value. Another arithmetic element is utilized as the former element to determine non-paid sums in a position of a due account of each consumer for processing coins by using an algorithm. The elements are related to purchase operations of consumers and purchase return events unsuitable for consumption or cancellation by cashiers of incorrect registration. United nations children's fund card is compulsory for the purchase operations. The due account of each consumer is between two determined limits.</p>
