2) We have already learned that most one-syllable et-nouns do not add -er in the indefinite plural.
For example: et fjell → mange fjell.
(NB! There is one important exception to this rule: et sted —> mange steder)
A few en/ei-nouns work the same way–with no ending in the indefinite plural:
| en ting | mange ting | (thing) |
| en/ei mil | mange mil | (Norwegian mile) |
| en ski | mange ski | (ski) |
| en/ei mus | mange mus | (mouse) |
| en feil | mange feil | (error, mistake) |
| en/et kilo | mange kilo | (kilogram) |
| en meter | mange meter | (meter) |
| en mygg | mange mygg | (mosquito) |
| en sko | mange sko | (shoe) |
| en kjeks | mange kjeks | (cracker) |

