Stripping date from serial rfid

Hi all. I have a RFID reader with USB output and wish to strip all data except for the last three digits then encode these as latched BCD outputs. As an absolute beginner with Arduino and suggestions would be appreciated thanks. I had thought of using a UART but the Arduino would be better. Paul Andrews

You cannot connect a USB slave device to an Arduino unless you use a USB Host shield. And I have no idea if a USB Host shield would recognize your RFID reader.

You can get RFID readers that can communicate directly with an Arduino (using Serial or SPI I think)