plantwise number range

Hi SAP Gurus

I m SAP SD Consultant. I have an assignment of giving number ranges to Billing documents at plant level

e.g

Plants Number Range of Billing Document

ADEL 00010000--00019999

ABAN 00020000---00029999

AMUM 00030000---00039999

ACAL 00040000---00049999

Please guide me treating me as a beginer

Regards

Rajesh