to be unplugged from the headphone port 140 for example after the desired virtual key has been selected the touch sensitive surface of the touchscreen 43 can be double tapped with a finger for example this tap gesture activates the selected virtual key as a result of which the associated digit is input another suitable tap gesture is a single tap with two fingertips in order to operate the selected virtual key a further gesture can be reserved for changing to and fro between digit input and buttons as in fig9 to 12 in this regard the gesture defined is a double tap with two fingertips for example this pauses or terminates digit input and places the focus on buttons as are shown in fig9 to 12 for example such buttons have the assigned functions u201c clear all digits u201d u201c clear last digit u201d u201c confirm input u201d and u201c back u201d for example on a credit transfer terminal the screen content presented by the touchscreen 43 is split into different regions for example a field containing the sum to be paid a field for the account number of the recipient and a region with the aforementioned four buttons for confirming or clearing the input digits suitable audible voice synthesis.