

Мне двадцать лет.
I am twenty years old.
В классе двадцать человек.
There are twenty people in the class.
Это стоит двадцать рублей?
Does this cost twenty rubles?
"двадцать" is in the lesson "Big numbers" (Level 4), along with 11 other useful words. LinDuo has 180 topic lessons like this one, 2,380 words in total. Every word has an illustration, a transcription and pronunciation in a female and a male voice. Just 10–15 minutes a day is enough to learn them all. Free, and works offline.