The norm in Norwegian is to write numbers from one to twelve using letters and the numbers from 13 and above using numbers. It is recommended not to mix letters and numbers within the same sentence (or even within the same paragraph or the same document), so it would be better to write “from one to fifty cars” or “from 1 to 50 cars” than “from one to 50 cars”. When spelt with letters, they are either spelt in one word (hundreogtrettito) or separately (hundre og tretti to).

The decimal mark in Norwegian is the comma and the thousands separator is a blank space, so 987654 divided by 100 equals 9 876,54. Not all Norwegians follow these rules, so pay attention when a website prompt you for a number as the website will usually tell you what decimal mark to use (or even prompt for the decimals in a separate field).

In Old Norse, numbers one through four were all inflected in three genders (masculine, feminine and neuter) and four cases (nominative, accusative, dative and genitive). In modern Norwegian, most of the inflection is gone. The official orthography only contains inflected forms of one, but some dialects have kept a larger portion. However, the case inflection is gone everywhere. The early Nynorsk orthography kept the gender inflection of all four numbers, but the forms gradually merged.

Numeral Literal Additional information
0 Null
1 Bokmål: én (masc.), éi (fem.), ett (neuter)
Nynorsk: éin (masc.), éi (fem), eitt (neuter)
In Bokmål, masc. and fem. are sometimes merged into a common gender (én). The common gender is inherited from written Danish and is therefore not allowed in Nynorsk, which has always used three genders. Origin: Old Norse einn (masc.), ein (fem.), eitt (neuter)
2 To Earlier tvo in Nynorsk. Origin: Old Norse tveir (masc.), tvær (fem.), tvau (neuter). Some dialects still uses tvei, tvæ and tvau.
3 Tre (tri) Earlier tri in Nynorsk, still part of the official orthography, but not to be used by the authorities. Origin: Old Norse þrír (masc.), þrjár (fem.), þrjú (neuter).
4 Fire Earlier fjore in Nynorsk, before gradually being replaced by fire. Origin: Danish fire, Old Norse fjórír (masc.), fjórar (fem.), fjǫgur (neuter).
5 Fem Origin: Old Norse fimm.
6 Seks Origin: Old Norse sex.
7 Sju (syv) The spelling syv was banned from the official orthography in 1951, but re-introduced in 2005. Nynorsk has always used sju (originally sjau). Origin: Old Norse sjau, Danish syv
8 Åtte Earlier åtta in Nynorsk. Origin: Old Norse átta.
9 Ni Earlier nio in Nynorsk. Origin: Old Norse níu.
10 Ti Earlier tio in Nynorsk. Origin: Old Norse tíu.
11 Elleve Origin: Old Norse ellifu.
12 Tolv Origin: Old Norse tólf.
13 Tretten Earlier trettan in Nynorsk. Origin: Old Norse þrettán.
14 Fjorten Earlier fjortan in Nynorsk. Origin: Old Norse fjórtán.
15 Femten Earlier femtan in Nynorsk. Origin: Old Norse fimtán.
16 Seksten Earlier sekstan in Nynorsk. Origin: Old Norse sextán.
17 Sytten Earlier sjauttan in Nynorsk. Origin: Old Norse sjautján.
18 Atten Earlier atjan in Nynorsk. Origin: Old Norse átján.
19 Nitten Earlier nitjan in Nynorsk. Origin: Old Norse nítján.
20 Tjue Earlier tyve in Bokmål and tjugo in Nynorsk. Origin: Old Norse tjogu, tuttugu, Danish tyve.
21 Tjueén Earlier én og tyve in Bokmål, ein og tjugo in Nynorsk (meaning “one and twenty”). As of 1951, tens are mentioned first (like in English “twenty one”). Old Norse used both tuttugu ok einn (“twenty and one”) and einn ok tuttugu (“one and twenty”).
22 Tjueto
23 Tjuetre
24 Tjuefire
25 Tjuefem
30 Tretti Earlier tredve in Bokmål. Origin: Old Norse þrír tigir (simplified and contracted to tretti), Danish tred(i)ve.
40 Førti Earlier førr in Bokmål, fyrti in Nynorsk. Origin: Old Norse fjórir tigir, fjórutigi (fyrti, førti), Danish fyrre (førr).
50 Femti Origin: Old Norse fimtigi.
60 Seksti Origin: Old Norse sex tigir.
70 Sytti Earlier sjautti in Nynorsk. Origin: Old Norse sjautigi.
80 Åtti Earlier åtteti in Nynorsk. Origin: Old Norse áttatigi, áttatiu.
90 Nitti Origin: Old Norse níu tigir.
100 (Ett) Hundre Earlier hundrede in Bokmål, hundrad in Nynorsk. Origin: Old Norse hundrað.
101 (Ett) hundre og én/éin May be spelt in one word (hundreogén).
102 (Ett) hundre og to
103 (Ett) hundre og tre
104 (Ett) hundre og fire
105 (Ett) hundre og fem
125 (Ett) hundre og tjuefem
200 To hundre
300 Tre hundre
400 Fire hundre
500 Fem hundre
1 000 (Ett) tusen Earlier tusund in Nynorsk. Origin: Old Norse þusund
2 000 To tusen
3 000 Tre tusen
4 000 Fire tusen
5 000 Fem tusen
1 000 000 Én million Origin: derived from Latin mille (“thousand”).
2 000 000 To millioner
3 000 000 Tre millioner
4 000 000 Fire millioner
5 000 000 Fem millioner
7 473 259 Sjumillionerfirehundreogsyttitretusentohundreogfemtini
1 000 000 000 Én milliard Origin: derived from French.