Abstract: A method of operating Automated Teller Machines, ATMs. An ATM dispenses currency, thereby depleting its supply, and requiring replenishment. Replenishment currently involves humans who (1) measure the currency content of an ATM, (2) compute an amount to be replenished, and (3) report the amounts replenished, when replenishment occurs. These human actions are error-prone. The invention eliminates all three steps. Under the invention, no actual measurement is made of currency content, for replenishment purposes. Instead, the content is estimated. Then, the estimate is used to compute an amount for replenishment. Replenishment occurs, but the fact of replenishment is inferred from signals received from the ATM, and not from a report from a human.