... tax-in.4, In the mode of calculator(CAL),it would apply the normal calculator's function . And if you connect ... . a.Connecting this device by USB cable to PC, it would show ''PC-KEYPAD'',it expresses now in the mode of ... KEYPAD. B.After pressing ''Mode'' ,the words ''PC-KEYPAD'' would disappear on LCD. It expresses now in the mode of ...