The invention concerns a device (1) comprising a digital keyboard (2) capable of being actuated by an operator for inputting figures of a particular digital value, display means (3) for displaying at least the input figures, validating means (5) capable of being actuated by an operator for validating a displayed digital value, and an input-aid system (6) comprising acquisition means (9) for acquiring the input figures as they are being input, and processing means (10) knowing the digital values which are valid, determining at each input of one figure based on said valid digital values at least one auxiliary figure which it associates with the set of already input figures to form therewith a proposed value, and transmitting said proposed value to the display means (2) for display.