| Sg | Pl | |
| Nom | hellusteinn | hellusteinar (rule) |
| Acc | hellustein (rule) | hellusteina (rule) |
| Dat | helluSteini (rule) | hellusteinum (rule) |
| Gen | helluSteins (rule) | hellusteina (rule) |
| Sg | Pl | |
| Nom | hellusteinninn (rule) | hellusteinarnir (rule) |
| Acc | hellusteininn (rule) | hellusteinana (rule) |
| Dat | hellusteininum (rule) | hellusteinunum (rule) |
| Gen | helluSteinsins (rule) | hellusteinanna (rule) |