Breakdown of В библиотеке семьдесят два словаря.
словарь
dictionary
в
in / to (direction)
библиотека
library
два
two
Questions & Answers about В библиотеке семьдесят два словаря.
Why is the word for dictionary (словаря) in the singular here? There are 72 of them!
In Russian, compound numbers follow the rule of their very last word. Since семьдесят два ends in два (two), the noun following it must be in the genitive singular case, making it словаря. It does not matter that 72 is a large amount!
Would we ever use две instead of два for 72?
How is the word семьдесят built?
It literally means "seven tens." It combines семь (seven) and десят (an old form of the word for ten). You will see this same -десят pattern in 50, 60, 70, and 80.
Why does библиотеке end in -е?
Because it is telling us where something is located ("in the library"). This requires the prepositional case. The dictionary form is библиотека, and the -а changes to -е to show location.