Postal codes in Nigeria are numeric, consisting of six digits.
NIPOST, the Nigerian Postal Service, divides the country into nine regions, which make up the first digit of the code.
The second and third digits, combined with the first, are the dispatch district for outgoing sorting.
The main postal head office in each region will have a postal code ending in 0001, so Garki Main HO in Abuja has the postal code 900001, Ikeja HO in Lagos has 100001, Lokoja in Kogi has 270001 and Port Harcourt has 500001.
In addition there are some postal code for some states in Nigeria, as Enugu's postal code is 400001, while Imo state's is 460001.