Using the database for the 1900 Norwegian census (Norwegian Historical Data Centre) - I ran a search limiting to men, first name starting with 'Ma', last name starting with 'Eri', born between 1850-1860 and living in Finnmark for the census.
Keep in mind that when a database is extracted to electronic form from handwritten originals there may be simple errors, handwriting which is difficult to read and interpret, etc. So you must broaden the range of POSSIBLE matches and clues to your "Matts Erikson Väärämäki".
The one I noticed in Finnmark (you should consider widening that location or trying different combinations of search criteria) -http://www.rhd.uit.no/folketellinger/ftliste_e.aspx?ft=1900&...
Norwegian censuses on NHDC website, instructions included (http://www.rhd.uit.no/indexeng.html
The database search wildcard which is enormously useful is '%'.