Thirty and Compound Numbers
Just like 20, the number 30 (тридцать) ends in the suffix -дцать.
To form compound numbers (like 31 or 32), simply say the tens word followed by the units word. A noun that follows declines based entirely on the last word in the sequence. For example, compounds ending in 1 act just like 1, while those ending in 2, 3, or 4 trigger the genitive singular.
| This book costs thirty-two rubles. | Эта книга стоит тридцать два рубля. |
| We have thirty-one tickets. | У нас есть тридцать один билет. |
Forty: The Exception
The number 40 does not follow the standard pattern for tens. It is a completely unique word: сорок.
| This is bus number forty. | Это автобус номер сорок. |
| I must write forty-three words. | Я должен написать сорок три слова. |
Fifty to Eighty
The numbers 50 through 80 are formed by combining the base digit with the suffix -десят (an old plural meaning "tens").
Watch out for the spelling: words like 50 (пятьдесят) and 60 (шестьдесят) keep the soft sign (ь) from their base digit right in the middle of the word, but do not have one at the end.
| This soup costs fifty-two rubles. | Этот суп стоит пятьдесят два рубля. |
| There is no bus number sixty here. | Здесь нет автобуса номер шестьдесят. |
| He is seventy-four years old. | Ему семьдесят четыре года. |
Ninety and One Hundred
The set of tens finishes with 90 (девяносто) and 100 (сто).
When counting above 100, keep combining the numbers sequentially. Unlike in English, you never use a word for "and"—simply place the ones digit right after the hundreds or tens word (e.g., 101 is literally "hundred one").
| My house is number one hundred, not ninety. | Мой дом — номер сто, а не девяносто. |
| I have ninety-three rubles. | У меня есть девяносто три рубля. |
| Anna has one hundred and one rubles. | У Анны есть сто один рубль. |