If you are a Norwegian business enterprise and have dealings with the customs authorities in an EU country, you will need an EORI number. You will receive such a number by applying to the customs authorities in the relevant EU country.
The EORI number (Economic Operator Registration and Identification number) is a unique identity number (customer number) from the customs authorities in the EU. You must use this number for all customs-related business in the EU.
You can read more about EORI numbers on the website of the European Commission.
Apply for an EORI number in Sweden here
Check the validity of an EORI number: EORI number validation