Declension of simple and complex numerals

In this article we talk about cardinal numerals and learn the way to change them (decline).

Cardinal numerals answer the question "Сколько?" [skol'ka] (How much/many?) and divide into simple, complex and compound - depending on what number answers this question and how it is written.

Simple numerals have one stem.
Шесть [shest'] - six, одиннадцать [adinatsat'] - eleven, сорок [sorak] - forty, сто [sto] - a hundred.

Complex numerals include two stems written in one word.
Пятьдесят [pidisyat] - fifty, семьдесят [sem'disyat] - seventy, девяносто [divyanosta] - ninety.

Compound numerals include several words written separately.
Двести сорок два [dvesti sorak dva] - 242, пятьсот сорок восемь [pitsot sorak vosim'] - 548, две тысячи тридцать два [dve tysichi tritsat' dva] - 2032.

Learning simple and complex numerals, you can notice that the number of stems depends on the amount of a number, i.e. complex numbers are counted from the number "пятьдесят" [pidisyat] (fifty). But the numeral "двадцать один" [dvatsat' adin] - twenty one - is a compound one.

Well, there are the basic rules for numerals' declension. It is better to divide them into groups according to common rules.
1. How decline numerals from one to five (1-5).
Один [adin], одного [adnavo], одному [adnamu], один [adin], одним [adnim], одном [adnom] - one.

Numerals "два" [dva], "три" [tri] and "четыре" [chityre] are declined in a certain way.
Два [dva], двух [dvukh], двум [dvum], два [dva], двумя [dvumya], двух [dvukh] - two.
Три [tri], трёх [tryokh], трём [tryom], три [tri], тремя [tryomya], трёх [tryokh] - three.
Четыре [chityri], четырёх [chityryokh], четырём [chityryom], четыре [chityri], четырьмя [chityr'mya], четырёх [chityryokh] - four.

Pay attention to the letter У [u], which is appeared in declension of the numeral "два" [dva] and the ending -МЯ, when we decline "два", "три" and "четыре" in the instrumental case.

2. How to decline numerals from five to thirty (5-30).

Remember the following rule: these numerals are declined according to declension rules of feminine nouns which end with the soft sign (Ь). Let's decline the numerals "пять" (5) and "двадцать" (20).
Пять [pyat'], пяти [pyati], пяти [pyati], пять [pyat'], пятью [pit'yu], пяти [pyati] - five.
Двадцать [dvatsat'], двадцати [dvatsati], двадцати [dvatsati], двадцать [dvatsat'], двадцатью [dvatsat'yu], двадцати [dvatsati] - twenty.

3. How to decline numerals from fifty to ninety (50-90).
In complex numerals we change both stems. Let's decline the numeral "шестьдесят" (60).
Шестьдесят [shisdisyat], шестидесяти [shistidisiti], шестидесяти [shistidisiti], шестьдесят [shisdisyat], шестьюдесятью [shistidisit'yu], шестидесяти [shistidisiti] - sixty.

4. How to decline numerals "полтора" [paltara] (1.5) "сто" [sto] (100), "сорок" [sorak] (40), "девяносто" [divinosta] (90).
We point out these numerals because they are declined otherwise. These numerals have only two forms: direct (nominative and accusative case) and indirect, i.e. these words are changed only in the following way:

Сто - ста [sto - sta] - a hundred
Девяносто - девяноста [divyanosta - divyanosta] - ninety.
Сорок - сорока [sorak - saraka] - forty.

Девяносто [divyanosta], девяноста [divyanosta], девяноста [divyanosta], девяносто [divyanosta], девяноста [divyanosta], девяноста [divyanosta].

These numerals do not have any other endings except for the ending "А". And the word "полтора" [paltara] (one and a half) has the letter У in indirect form.

Полтора - полутора [paltara - palutara].