How numbers work in Norwegian
Norwegian has separate words for 0 to 12: null, en, to … elleve, tolv. From 13 to 19 the numbers end in -ten: tretten, fjorten, femten, seksten, sytten, atten, nitten. Seven has two accepted forms: sju and syv.
The tens end in -ti: tjue, tretti, førti, femti, seksti, sytti, åtti, nitti. The unit is attached without a space: tjueen, trettifem, nittini.
Until 1951 Norwegian, like Danish and German, put the unit first: enogtjue (21), femogtretti (35). You will still hear this from older speakers and it is not wrong, but courses teach the newer ten-first order.
Hundre and tusen are often said without ett: hundre, tusen, to hundre, to tusen. A million is en million, plural to millioner.
The ordinals up to ten are første, andre, tredje, fjerde, femte, sjette, sjuende (or syvende), åttende, niende, tiende.