The device has two movable displays (1,5), respectively carrying unit and tenth digits, where the display (1) comprises 31 primary teeth arranged in three complete series. The display (1) has four secondary teeth (4) on its outer periphery to drive the display (5) for changing the tenth digits. The display (5) has 4 Maltese cross shaped divisions (6a), each intended to contact the teeth (4) and a positioning pin (7).
展开▼
