Also 101 becomes singular again, as on "101 kot".

There are websites that capture these rules for all common languages, to assist localization and translators.

https://docs.translatehouse.org/projects/localization-guide/...

English is

nplurals=2; plural=(n != 1);

Russian is much more complex:

nplurals=3; plural=(n%10==1 && n%100!=11 ? 0 : n%10>=2 && n%10<=4 && (n%100<10 || n%100>=20) ? 1 : 2);