A calculating device includes a key input unit, a display and a processor. The processor performs: calculating a payment data item from input calculation data including numerical data items and operation data items; in the case where input of a first deposit data item and an instruction of a change function are received, controlling the display to display a calculation result data item obtained by subtracting the payment data item from the first deposit data item, as a first change data item; and in the state where the display displays the first change data item, even though the input calculation data are not re-input, if a second deposit data item and an instruction of the change function are received, controlling the display to display a calculation result data item obtained by subtracting the payment data item from the second deposit data item, as a second change data item.