... :This is a Two -in - one device,It compatible PC Keypad and 12bit Commercial Calculator with TaxCalculation ... the battery for a long time.3, The device applies to account by normal operations, such as" +,- ,*,/, %" ... 's function . And if you connect it by USB cable to your PC,you may send the results ... .Connecting this device by USB cable to PC, it would show ''PC-KEYPAD'',it expresses now in the mode of ...