Gst registration quantity cannot be Specified as it depends upon your nature of business, structure of business and as per your requirements.
The GST regime allows only one registration against a PAN, but firms with multiple business verticals can choose to apply for multiple registration numbers against a corresponding PAN number.
Further any branch or a warehouse or another office of same registered entity in more than one states are required to obtain separate registration under GST as a taxpayer. Thus a company having a PAN has to obtain multiple GST registration all over the country as per its requirements.
Therefore more than one registration can be obtained on a Single PAN.