Instead of ДВА РЕБЁНКА (two children) Russian normally say ДВОЕ ДЕТЕЙ (twosome of children). There are NINE of these collective numerals, from two to ten, but only the first free are common:
ДВОЕ a twosome
ТРОЕ a threesome
ЧЕТВЕРО a foursome
The others are ПЯТЕРО, ШЕСТЕРО, СЕМЕРО, ВОСЬМЕРО, ДЕВЯТЕРО, ДЕСЯТЕРО.
You need these collective numerals:
- when counting children (ДЕТИ) and men (МУЖЧИНЫ) У неё двое детей. (She has two children). Двое мужчин (Two men) – not ДВА МУЖЧИНЫ
- when counting words which have no singular forms: часы (watch), брюки (trousers), сутки (twenty-four hours). У меня ДВОЕ ЧАСОВ. (I have two watches) В поезде мы ехали ТРОЕ СУТОК. (We spent three days and nights on the train. )
- in phrases such as “There are four of us” – Нас ЧЕТВЕРО. Нас было ТРОЕ (There were three of us)
EXTRA: More on Collective Numerals
Optionally, collective numerals can be used for a groups of males (not females or mixed groups): ДВОЕ СОЛДАТ (two soldiers), ТРОЕ УЧИТЕЛЕЙ (three teachers).
BUT!! ТРОЕ МИНИСТРОВ (a threesome of male government ministers) would sound disrespectful – ТРИ МИНИСТРА is more polite.
Declension of collective numerals
| N | G | D | A | I | P |
| двое | двоих | двоим | двое (inan.) двоих (an.) | двоими | двоих |
| трое | троих | троим | трое (inan.) троих (an.) | троими | троих |
| четверо | четверых | четверым | четверо (inan.) четверых (an.) | четверыми | четверых |
The others declines like ЧЕТВЕРО
Key Phrases:
НОМЕР НА ДВОИХ (in a hotel – a room for two people), СТОЛИК НА ДВОИХ (in a restaurant – a table for two )
РАБОТАТЬ ЗА ТРОИХ (to work for three – do as much as three people)