Russian Genitive Plural with a Fleeting Vowel

Did you know that, in the Genitive plural, nouns with a stem ending in two (or more) consonants need a vowel (o or e) which is inserted before the last consonant. In most cases, e is inserted if the stem end in ж/ш/ч/ц/щ/soft с + consonant or a soft consonant + consonant, and о is used if the stem ends in another combination of consonants.

For example,

Окно – окон

Студентка – студенток

Чашка – чашек

Ручка – ручек

Кружка – кружек

Песня – песен