Counting from zero, plus the round numbers you need first.

• nulzero (0)
• en / etone (1) — 'en' common gender, 'et' neuter
• totwo (2)
• trethree (3)
• firefour (4)
• femfive (5)
• sekssix (6)
• syvseven (7)
• otteeight (8)
• ninine (9)
• titen (10)
• tyvetwenty (20)
• tredivethirty (30)
• halvtredsfifty (50)
• hundredeone hundred (100)